Import posix_spawn from Gnulib.

posix_spawn is less error-prone than vfork + exec, and can make use of
system-specific optimizations like `clone' on Linux.  Import Gnulib
replacement so that we can use recent additions like
`posix_spawn_file_actions_addchdir'.

The only manual change are to admin/merge-gnulib and .gitignore.  All
other changes are due to rerunning merge-gnulib.

* admin/merge-gnulib (GNULIB_MODULES): Add posix_spawn-related
modules.
* .gitignore: Add new generated files.

27 files changed, 3612 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index bf7e9349813..f9c0fae4f60 100644
--- a/.gitignore
+++ b/.gitignore
@@ -65,7 +65,9 @@ lib/ieee754.h
 lib/inttypes.h
 lib/libgnu.a
 lib/limits.h
+lib/sched.h
 lib/signal.h
+lib/spawn.h
 lib/std*.h
 !lib/std*.in.h
 !lib/stdio-impl.h
diff --git a/admin/merge-gnulib b/admin/merge-gnulib
index 880dc5eef53..f1ed2da69e5 100755
--- a/admin/merge-gnulib
+++ b/admin/merge-gnulib
@@ -39,7 +39,14 @@ GNULIB_MODULES='
   getloadavg getopt-gnu getrandom gettime gettimeofday gitlog-to-changelog
   ieee754-h ignore-value intprops largefile libgmp lstat
   manywarnings memmem-simple mempcpy memrchr minmax mkostemp mktime nstrftime
-  pathmax pipe2 pselect pthread_sigmask
+  pathmax pipe2
+  posix_spawn posix_spawn_file_actions_addchdir
+  posix_spawn_file_actions_adddup2 posix_spawn_file_actions_destroy
+  posix_spawn_file_actions_init
+  posix_spawnattr_destroy posix_spawnattr_init
+  posix_spawnattr_setflags posix_spawnattr_setpgroup
+  posix_spawnattr_setsigdefault posix_spawnattr_setsigmask
+  pselect pthread_sigmask
   qcopy-acl readlink readlinkat regex
   sig2str sigdescr_np socklen stat-time std-gnu11 stdalign stddef stdio
   stpcpy strnlen strtoimax symlink sys_stat sys_time
diff --git a/lib/gnulib.mk.in b/lib/gnulib.mk.in
index a37f9278a31..209c7eef299 100644
--- a/lib/gnulib.mk.in
+++ b/lib/gnulib.mk.in
@@ -130,6 +130,17 @@
 #  nstrftime \
 #  pathmax \
 #  pipe2 \
+#  posix_spawn \
+#  posix_spawn_file_actions_addchdir \
+#  posix_spawn_file_actions_adddup2 \
+#  posix_spawn_file_actions_destroy \
+#  posix_spawn_file_actions_init \
+#  posix_spawnattr_destroy \
+#  posix_spawnattr_init \
+#  posix_spawnattr_setflags \
+#  posix_spawnattr_setpgroup \
+#  posix_spawnattr_setsigdefault \
+#  posix_spawnattr_setsigmask \
 #  pselect \
 #  pthread_sigmask \
 #  qcopy-acl \
@@ -393,6 +404,29 @@ GNULIB_PIPE2 = @GNULIB_PIPE2@
 GNULIB_POPEN = @GNULIB_POPEN@
 GNULIB_POSIX_MEMALIGN = @GNULIB_POSIX_MEMALIGN@
 GNULIB_POSIX_OPENPT = @GNULIB_POSIX_OPENPT@
+GNULIB_POSIX_SPAWN = @GNULIB_POSIX_SPAWN@
+GNULIB_POSIX_SPAWNATTR_DESTROY = @GNULIB_POSIX_SPAWNATTR_DESTROY@
+GNULIB_POSIX_SPAWNATTR_GETFLAGS = @GNULIB_POSIX_SPAWNATTR_GETFLAGS@
+GNULIB_POSIX_SPAWNATTR_GETPGROUP = @GNULIB_POSIX_SPAWNATTR_GETPGROUP@
+GNULIB_POSIX_SPAWNATTR_GETSCHEDPARAM = @GNULIB_POSIX_SPAWNATTR_GETSCHEDPARAM@
+GNULIB_POSIX_SPAWNATTR_GETSCHEDPOLICY = @GNULIB_POSIX_SPAWNATTR_GETSCHEDPOLICY@
+GNULIB_POSIX_SPAWNATTR_GETSIGDEFAULT = @GNULIB_POSIX_SPAWNATTR_GETSIGDEFAULT@
+GNULIB_POSIX_SPAWNATTR_GETSIGMASK = @GNULIB_POSIX_SPAWNATTR_GETSIGMASK@
+GNULIB_POSIX_SPAWNATTR_INIT = @GNULIB_POSIX_SPAWNATTR_INIT@
+GNULIB_POSIX_SPAWNATTR_SETFLAGS = @GNULIB_POSIX_SPAWNATTR_SETFLAGS@
+GNULIB_POSIX_SPAWNATTR_SETPGROUP = @GNULIB_POSIX_SPAWNATTR_SETPGROUP@
+GNULIB_POSIX_SPAWNATTR_SETSCHEDPARAM = @GNULIB_POSIX_SPAWNATTR_SETSCHEDPARAM@
+GNULIB_POSIX_SPAWNATTR_SETSCHEDPOLICY = @GNULIB_POSIX_SPAWNATTR_SETSCHEDPOLICY@
+GNULIB_POSIX_SPAWNATTR_SETSIGDEFAULT = @GNULIB_POSIX_SPAWNATTR_SETSIGDEFAULT@
+GNULIB_POSIX_SPAWNATTR_SETSIGMASK = @GNULIB_POSIX_SPAWNATTR_SETSIGMASK@
+GNULIB_POSIX_SPAWNP = @GNULIB_POSIX_SPAWNP@
+GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR = @GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR@
+GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE = @GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE@
+GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2 = @GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2@
+GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR = @GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR@
+GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN = @GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN@
+GNULIB_POSIX_SPAWN_FILE_ACTIONS_DESTROY = @GNULIB_POSIX_SPAWN_FILE_ACTIONS_DESTROY@
+GNULIB_POSIX_SPAWN_FILE_ACTIONS_INIT = @GNULIB_POSIX_SPAWN_FILE_ACTIONS_INIT@
 GNULIB_PREAD = @GNULIB_PREAD@
 GNULIB_PRINTF = @GNULIB_PRINTF@
 GNULIB_PRINTF_POSIX = @GNULIB_PRINTF_POSIX@
@@ -425,6 +459,7 @@ GNULIB_RMDIR = @GNULIB_RMDIR@
 GNULIB_RPMATCH = @GNULIB_RPMATCH@
 GNULIB_SCANDIR = @GNULIB_SCANDIR@
 GNULIB_SCANF = @GNULIB_SCANF@
+GNULIB_SCHED_YIELD = @GNULIB_SCHED_YIELD@
 GNULIB_SECURE_GETENV = @GNULIB_SECURE_GETENV@
 GNULIB_SELECT = @GNULIB_SELECT@
 GNULIB_SETENV = @GNULIB_SETENV@
@@ -634,6 +669,11 @@ HAVE_POPEN = @HAVE_POPEN@
 HAVE_POSIX_MEMALIGN = @HAVE_POSIX_MEMALIGN@
 HAVE_POSIX_OPENPT = @HAVE_POSIX_OPENPT@
 HAVE_POSIX_SIGNALBLOCKING = @HAVE_POSIX_SIGNALBLOCKING@
+HAVE_POSIX_SPAWN = @HAVE_POSIX_SPAWN@
+HAVE_POSIX_SPAWNATTR_T = @HAVE_POSIX_SPAWNATTR_T@
+HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR = @HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR@
+HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR = @HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR@
+HAVE_POSIX_SPAWN_FILE_ACTIONS_T = @HAVE_POSIX_SPAWN_FILE_ACTIONS_T@
 HAVE_PREAD = @HAVE_PREAD@
 HAVE_PSELECT = @HAVE_PSELECT@
 HAVE_PTHREAD_SIGMASK = @HAVE_PTHREAD_SIGMASK@
@@ -655,6 +695,8 @@ HAVE_RENAMEAT = @HAVE_RENAMEAT@
 HAVE_REWINDDIR = @HAVE_REWINDDIR@
 HAVE_RPMATCH = @HAVE_RPMATCH@
 HAVE_SCANDIR = @HAVE_SCANDIR@
+HAVE_SCHED_H = @HAVE_SCHED_H@
+HAVE_SCHED_YIELD = @HAVE_SCHED_YIELD@
 HAVE_SECURE_GETENV = @HAVE_SECURE_GETENV@
 HAVE_SETENV = @HAVE_SETENV@
 HAVE_SETHOSTNAME = @HAVE_SETHOSTNAME@
@@ -669,6 +711,7 @@ HAVE_SIGNED_WCHAR_T = @HAVE_SIGNED_WCHAR_T@
 HAVE_SIGNED_WINT_T = @HAVE_SIGNED_WINT_T@
 HAVE_SIGSET_T = @HAVE_SIGSET_T@
 HAVE_SLEEP = @HAVE_SLEEP@
+HAVE_SPAWN_H = @HAVE_SPAWN_H@
 HAVE_STDINT_H = @HAVE_STDINT_H@
 HAVE_STPCPY = @HAVE_STPCPY@
 HAVE_STPNCPY = @HAVE_STPNCPY@
@@ -683,6 +726,7 @@ HAVE_STRTOLD = @HAVE_STRTOLD@
 HAVE_STRTOLL = @HAVE_STRTOLL@
 HAVE_STRTOULL = @HAVE_STRTOULL@
 HAVE_STRUCT_RANDOM_DATA = @HAVE_STRUCT_RANDOM_DATA@
+HAVE_STRUCT_SCHED_PARAM = @HAVE_STRUCT_SCHED_PARAM@
 HAVE_STRUCT_SIGACTION_SA_SIGACTION = @HAVE_STRUCT_SIGACTION_SA_SIGACTION@
 HAVE_STRUCT_TIMEVAL = @HAVE_STRUCT_TIMEVAL@
 HAVE_STRVERSCMP = @HAVE_STRVERSCMP@
@@ -782,6 +826,7 @@ LIB_EACCESS = @LIB_EACCESS@
 LIB_EXECINFO = @LIB_EXECINFO@
 LIB_GETRANDOM = @LIB_GETRANDOM@
 LIB_MATH = @LIB_MATH@
+LIB_POSIX_SPAWN = @LIB_POSIX_SPAWN@
 LIB_PTHREAD = @LIB_PTHREAD@
 LIB_PTHREAD_SIGMASK = @LIB_PTHREAD_SIGMASK@
 LIB_TIMER_TIME = @LIB_TIMER_TIME@
@@ -805,7 +850,9 @@ NEXT_AS_FIRST_DIRECTIVE_FCNTL_H = @NEXT_AS_FIRST_DIRECTIVE_FCNTL_H@
 NEXT_AS_FIRST_DIRECTIVE_GETOPT_H = @NEXT_AS_FIRST_DIRECTIVE_GETOPT_H@
 NEXT_AS_FIRST_DIRECTIVE_INTTYPES_H = @NEXT_AS_FIRST_DIRECTIVE_INTTYPES_H@
 NEXT_AS_FIRST_DIRECTIVE_LIMITS_H = @NEXT_AS_FIRST_DIRECTIVE_LIMITS_H@
+NEXT_AS_FIRST_DIRECTIVE_SCHED_H = @NEXT_AS_FIRST_DIRECTIVE_SCHED_H@
 NEXT_AS_FIRST_DIRECTIVE_SIGNAL_H = @NEXT_AS_FIRST_DIRECTIVE_SIGNAL_H@
+NEXT_AS_FIRST_DIRECTIVE_SPAWN_H = @NEXT_AS_FIRST_DIRECTIVE_SPAWN_H@
 NEXT_AS_FIRST_DIRECTIVE_STDDEF_H = @NEXT_AS_FIRST_DIRECTIVE_STDDEF_H@
 NEXT_AS_FIRST_DIRECTIVE_STDINT_H = @NEXT_AS_FIRST_DIRECTIVE_STDINT_H@
 NEXT_AS_FIRST_DIRECTIVE_STDIO_H = @NEXT_AS_FIRST_DIRECTIVE_STDIO_H@
@@ -824,7 +871,9 @@ NEXT_FCNTL_H = @NEXT_FCNTL_H@
 NEXT_GETOPT_H = @NEXT_GETOPT_H@
 NEXT_INTTYPES_H = @NEXT_INTTYPES_H@
 NEXT_LIMITS_H = @NEXT_LIMITS_H@
+NEXT_SCHED_H = @NEXT_SCHED_H@
 NEXT_SIGNAL_H = @NEXT_SIGNAL_H@
+NEXT_SPAWN_H = @NEXT_SPAWN_H@
 NEXT_STDDEF_H = @NEXT_STDDEF_H@
 NEXT_STDINT_H = @NEXT_STDINT_H@
 NEXT_STDIO_H = @NEXT_STDIO_H@
@@ -946,6 +995,12 @@ REPLACE_OPENDIR = @REPLACE_OPENDIR@
 REPLACE_PERROR = @REPLACE_PERROR@
 REPLACE_POPEN = @REPLACE_POPEN@
 REPLACE_POSIX_MEMALIGN = @REPLACE_POSIX_MEMALIGN@
+REPLACE_POSIX_SPAWN = @REPLACE_POSIX_SPAWN@
+REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR = @REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR@
+REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE = @REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE@
+REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2 = @REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2@
+REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR = @REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR@
+REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN = @REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN@
 REPLACE_PREAD = @REPLACE_PREAD@
 REPLACE_PRINTF = @REPLACE_PRINTF@
 REPLACE_PSELECT = @REPLACE_PSELECT@
@@ -967,6 +1022,7 @@ REPLACE_REMOVE = @REPLACE_REMOVE@
 REPLACE_RENAME = @REPLACE_RENAME@
 REPLACE_RENAMEAT = @REPLACE_RENAMEAT@
 REPLACE_RMDIR = @REPLACE_RMDIR@
+REPLACE_SCHED_YIELD = @REPLACE_SCHED_YIELD@
 REPLACE_SELECT = @REPLACE_SELECT@
 REPLACE_SETENV = @REPLACE_SETENV@
 REPLACE_SETSTATE = @REPLACE_SETSTATE@
@@ -1108,11 +1164,13 @@ gamegroup = @gamegroup@
 gameuser = @gameuser@
 gl_GNULIB_ENABLED_03e0aaad4cb89ca757653bd367a6ccb7 = @gl_GNULIB_ENABLED_03e0aaad4cb89ca757653bd367a6ccb7@
 gl_GNULIB_ENABLED_260941c0e5dc67ec9e87d1fb321c300b = @gl_GNULIB_ENABLED_260941c0e5dc67ec9e87d1fb321c300b@
+gl_GNULIB_ENABLED_332607f759618fb73dfc3076748afea7 = @gl_GNULIB_ENABLED_332607f759618fb73dfc3076748afea7@
 gl_GNULIB_ENABLED_5264294aa0a5557541b53c8c741f7f31 = @gl_GNULIB_ENABLED_5264294aa0a5557541b53c8c741f7f31@
 gl_GNULIB_ENABLED_6099e9737f757db36c47fa9d9f02e88c = @gl_GNULIB_ENABLED_6099e9737f757db36c47fa9d9f02e88c@
 gl_GNULIB_ENABLED_682e609604ccaac6be382e4ee3a4eaec = @gl_GNULIB_ENABLED_682e609604ccaac6be382e4ee3a4eaec@
 gl_GNULIB_ENABLED_a9786850e999ae65a836a6041e8e5ed1 = @gl_GNULIB_ENABLED_a9786850e999ae65a836a6041e8e5ed1@
 gl_GNULIB_ENABLED_be453cec5eecf5731a274f2de7f2db36 = @gl_GNULIB_ENABLED_be453cec5eecf5731a274f2de7f2db36@
+gl_GNULIB_ENABLED_cdeb0f2aaf9d280baa6526bfa1b07f70 = @gl_GNULIB_ENABLED_cdeb0f2aaf9d280baa6526bfa1b07f70@
 gl_GNULIB_ENABLED_cloexec = @gl_GNULIB_ENABLED_cloexec@
 gl_GNULIB_ENABLED_dirfd = @gl_GNULIB_ENABLED_dirfd@
 gl_GNULIB_ENABLED_ef07dc4b3077c11ea9cef586db4e5955 = @gl_GNULIB_ENABLED_ef07dc4b3077c11ea9cef586db4e5955@
@@ -1124,6 +1182,7 @@ gl_GNULIB_ENABLED_lchmod = @gl_GNULIB_ENABLED_lchmod@
 gl_GNULIB_ENABLED_open = @gl_GNULIB_ENABLED_open@
 gl_GNULIB_ENABLED_rawmemchr = @gl_GNULIB_ENABLED_rawmemchr@
 gl_GNULIB_ENABLED_scratch_buffer = @gl_GNULIB_ENABLED_scratch_buffer@
+gl_GNULIB_ENABLED_strchrnul = @gl_GNULIB_ENABLED_strchrnul@
 gl_GNULIB_ENABLED_strtoll = @gl_GNULIB_ENABLED_strtoll@
 gl_GNULIB_ENABLED_utimens = @gl_GNULIB_ENABLED_utimens@
 gl_LIBOBJS = @gl_LIBOBJS@
@@ -2270,6 +2329,140 @@ libgnu_a_SOURCES += pipe2.c
 endif
 ## end   gnulib module pipe2
 
+## begin gnulib module posix_spawn
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawn))
+
+
+EXTRA_DIST += spawn.c
+
+EXTRA_libgnu_a_SOURCES += spawn.c
+
+endif
+## end   gnulib module posix_spawn
+
+## begin gnulib module posix_spawn-internal
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawn-internal))
+
+ifneq (,$(gl_GNULIB_ENABLED_332607f759618fb73dfc3076748afea7))
+
+endif
+EXTRA_DIST += spawn_int.h spawni.c
+
+EXTRA_libgnu_a_SOURCES += spawni.c
+
+endif
+## end   gnulib module posix_spawn-internal
+
+## begin gnulib module posix_spawn_file_actions_addchdir
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawn_file_actions_addchdir))
+
+
+EXTRA_DIST += spawn_faction_addchdir.c spawn_int.h
+
+EXTRA_libgnu_a_SOURCES += spawn_faction_addchdir.c
+
+endif
+## end   gnulib module posix_spawn_file_actions_addchdir
+
+## begin gnulib module posix_spawn_file_actions_adddup2
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawn_file_actions_adddup2))
+
+
+EXTRA_DIST += spawn_faction_adddup2.c spawn_int.h
+
+EXTRA_libgnu_a_SOURCES += spawn_faction_adddup2.c
+
+endif
+## end   gnulib module posix_spawn_file_actions_adddup2
+
+## begin gnulib module posix_spawn_file_actions_destroy
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawn_file_actions_destroy))
+
+
+EXTRA_DIST += spawn_faction_destroy.c
+
+EXTRA_libgnu_a_SOURCES += spawn_faction_destroy.c
+
+endif
+## end   gnulib module posix_spawn_file_actions_destroy
+
+## begin gnulib module posix_spawn_file_actions_init
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawn_file_actions_init))
+
+
+EXTRA_DIST += spawn_faction_init.c spawn_int.h
+
+EXTRA_libgnu_a_SOURCES += spawn_faction_init.c
+
+endif
+## end   gnulib module posix_spawn_file_actions_init
+
+## begin gnulib module posix_spawnattr_destroy
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawnattr_destroy))
+
+
+EXTRA_DIST += spawnattr_destroy.c
+
+EXTRA_libgnu_a_SOURCES += spawnattr_destroy.c
+
+endif
+## end   gnulib module posix_spawnattr_destroy
+
+## begin gnulib module posix_spawnattr_init
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawnattr_init))
+
+
+EXTRA_DIST += spawnattr_init.c
+
+EXTRA_libgnu_a_SOURCES += spawnattr_init.c
+
+endif
+## end   gnulib module posix_spawnattr_init
+
+## begin gnulib module posix_spawnattr_setflags
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawnattr_setflags))
+
+
+EXTRA_DIST += spawnattr_setflags.c
+
+EXTRA_libgnu_a_SOURCES += spawnattr_setflags.c
+
+endif
+## end   gnulib module posix_spawnattr_setflags
+
+## begin gnulib module posix_spawnattr_setpgroup
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawnattr_setpgroup))
+
+
+EXTRA_DIST += spawnattr_setpgroup.c
+
+EXTRA_libgnu_a_SOURCES += spawnattr_setpgroup.c
+
+endif
+## end   gnulib module posix_spawnattr_setpgroup
+
+## begin gnulib module posix_spawnattr_setsigdefault
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawnattr_setsigdefault))
+
+
+EXTRA_DIST += spawnattr_setdefault.c
+
+EXTRA_libgnu_a_SOURCES += spawnattr_setdefault.c
+
+endif
+## end   gnulib module posix_spawnattr_setsigdefault
+
+## begin gnulib module posix_spawnattr_setsigmask
+ifeq (,$(OMIT_GNULIB_MODULE_posix_spawnattr_setsigmask))
+
+
+EXTRA_DIST += spawnattr_setsigmask.c
+
+EXTRA_libgnu_a_SOURCES += spawnattr_setsigmask.c
+
+endif
+## end   gnulib module posix_spawnattr_setsigmask
+
 ## begin gnulib module pselect
 ifeq (,$(OMIT_GNULIB_MODULE_pselect))
 
@@ -2357,6 +2550,39 @@ EXTRA_DIST += root-uid.h
 endif
 ## end   gnulib module root-uid
 
+## begin gnulib module sched
+ifeq (,$(OMIT_GNULIB_MODULE_sched))
+
+BUILT_SOURCES += sched.h
+
+# We need the following in order to create a replacement for <sched.h> when
+# the system doesn't have one.
+sched.h: sched.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(WARN_ON_USE_H)
+        $(AM_V_GEN)rm -f $@-t $@ && \
+        { echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
+          sed -e 's|@''GUARD_PREFIX''@|GL|g' \
+              -e 's|@''HAVE_SCHED_H''@|$(HAVE_SCHED_H)|g' \
+              -e 's|@''HAVE_SYS_CDEFS_H''@|$(HAVE_SYS_CDEFS_H)|g' \
+              -e 's|@''INCLUDE_NEXT''@|$(INCLUDE_NEXT)|g' \
+              -e 's|@''PRAGMA_SYSTEM_HEADER''@|@PRAGMA_SYSTEM_HEADER@|g' \
+              -e 's|@''PRAGMA_COLUMNS''@|@PRAGMA_COLUMNS@|g' \
+              -e 's|@''NEXT_SCHED_H''@|$(NEXT_SCHED_H)|g' \
+              -e 's|@''HAVE_STRUCT_SCHED_PARAM''@|$(HAVE_STRUCT_SCHED_PARAM)|g' \
+              -e 's/@''GNULIB_SCHED_YIELD''@/$(GNULIB_SCHED_YIELD)/g' \
+              -e 's|@''HAVE_SCHED_YIELD''@|$(HAVE_SCHED_YIELD)|g' \
+              -e 's|@''REPLACE_SCHED_YIELD''@|$(REPLACE_SCHED_YIELD)|g' \
+              -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \
+              -e '/definition of _GL_WARN_ON_USE/r $(WARN_ON_USE_H)' \
+              < $(srcdir)/sched.in.h; \
+        } > $@-t && \
+        mv $@-t $@
+MOSTLYCLEANFILES += sched.h sched.h-t
+
+EXTRA_DIST += sched.in.h
+
+endif
+## end   gnulib module sched
+
 ## begin gnulib module scratch_buffer
 ifeq (,$(OMIT_GNULIB_MODULE_scratch_buffer))
 
@@ -2491,6 +2717,69 @@ EXTRA_DIST += warn-on-use.h
 endif
 ## end   gnulib module snippet/warn-on-use
 
+## begin gnulib module spawn
+ifeq (,$(OMIT_GNULIB_MODULE_spawn))
+
+BUILT_SOURCES += spawn.h
+
+# We need the following in order to create a replacement for <spawn.h> when
+# the system doesn't have one.
+spawn.h: spawn.in.h $(top_builddir)/config.status $(CXXDEFS_H) $(ARG_NONNULL_H) $(WARN_ON_USE_H)
+        $(AM_V_GEN)rm -f $@-t $@ && \
+        { echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
+          sed -e 's|@''GUARD_PREFIX''@|GL|g' \
+              -e 's|@''HAVE_SPAWN_H''@|$(HAVE_SPAWN_H)|g' \
+              -e 's|@''INCLUDE_NEXT''@|$(INCLUDE_NEXT)|g' \
+              -e 's|@''PRAGMA_SYSTEM_HEADER''@|@PRAGMA_SYSTEM_HEADER@|g' \
+              -e 's|@''PRAGMA_COLUMNS''@|@PRAGMA_COLUMNS@|g' \
+              -e 's|@''NEXT_SPAWN_H''@|$(NEXT_SPAWN_H)|g' \
+              -e 's/@''GNULIB_POSIX_SPAWN''@/$(GNULIB_POSIX_SPAWN)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNP''@/$(GNULIB_POSIX_SPAWNP)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWN_FILE_ACTIONS_INIT''@/$(GNULIB_POSIX_SPAWN_FILE_ACTIONS_INIT)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR''@/$(GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE''@/$(GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2''@/$(GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR''@/$(GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN''@/$(GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWN_FILE_ACTIONS_DESTROY''@/$(GNULIB_POSIX_SPAWN_FILE_ACTIONS_DESTROY)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_INIT''@/$(GNULIB_POSIX_SPAWNATTR_INIT)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_GETFLAGS''@/$(GNULIB_POSIX_SPAWNATTR_GETFLAGS)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_SETFLAGS''@/$(GNULIB_POSIX_SPAWNATTR_SETFLAGS)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_GETPGROUP''@/$(GNULIB_POSIX_SPAWNATTR_GETPGROUP)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_SETPGROUP''@/$(GNULIB_POSIX_SPAWNATTR_SETPGROUP)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_GETSCHEDPARAM''@/$(GNULIB_POSIX_SPAWNATTR_GETSCHEDPARAM)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_SETSCHEDPARAM''@/$(GNULIB_POSIX_SPAWNATTR_SETSCHEDPARAM)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_GETSCHEDPOLICY''@/$(GNULIB_POSIX_SPAWNATTR_GETSCHEDPOLICY)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_SETSCHEDPOLICY''@/$(GNULIB_POSIX_SPAWNATTR_SETSCHEDPOLICY)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_GETSIGDEFAULT''@/$(GNULIB_POSIX_SPAWNATTR_GETSIGDEFAULT)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_SETSIGDEFAULT''@/$(GNULIB_POSIX_SPAWNATTR_SETSIGDEFAULT)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_GETSIGMASK''@/$(GNULIB_POSIX_SPAWNATTR_GETSIGMASK)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_SETSIGMASK''@/$(GNULIB_POSIX_SPAWNATTR_SETSIGMASK)/g' \
+              -e 's/@''GNULIB_POSIX_SPAWNATTR_DESTROY''@/$(GNULIB_POSIX_SPAWNATTR_DESTROY)/g' \
+              -e 's|@''HAVE_POSIX_SPAWN''@|$(HAVE_POSIX_SPAWN)|g' \
+              -e 's|@''HAVE_POSIX_SPAWNATTR_T''@|$(HAVE_POSIX_SPAWNATTR_T)|g' \
+              -e 's|@''HAVE_POSIX_SPAWN_FILE_ACTIONS_T''@|$(HAVE_POSIX_SPAWN_FILE_ACTIONS_T)|g' \
+              -e 's|@''HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR''@|$(HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR)|g' \
+              -e 's|@''HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR''@|$(HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR)|g' \
+              -e 's|@''REPLACE_POSIX_SPAWN''@|$(REPLACE_POSIX_SPAWN)|g' \
+              -e 's|@''REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR''@|$(REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR)|g' \
+              -e 's|@''REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE''@|$(REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE)|g' \
+              -e 's|@''REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2''@|$(REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2)|g' \
+              -e 's|@''REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR''@|$(REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR)|g' \
+              -e 's|@''REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN''@|$(REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN)|g' \
+              -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \
+              -e '/definition of _GL_ARG_NONNULL/r $(ARG_NONNULL_H)' \
+              -e '/definition of _GL_WARN_ON_USE/r $(WARN_ON_USE_H)' \
+              < $(srcdir)/spawn.in.h; \
+        } > $@-t && \
+        mv $@-t $@
+MOSTLYCLEANFILES += spawn.h spawn.h-t
+
+EXTRA_DIST += spawn.in.h
+
+endif
+## end   gnulib module spawn
+
 ## begin gnulib module stat-time
 ifeq (,$(OMIT_GNULIB_MODULE_stat-time))
 
@@ -2885,6 +3174,19 @@ EXTRA_libgnu_a_SOURCES += stpcpy.c
 endif
 ## end   gnulib module stpcpy
 
+## begin gnulib module strchrnul
+ifeq (,$(OMIT_GNULIB_MODULE_strchrnul))
+
+ifneq (,$(gl_GNULIB_ENABLED_strchrnul))
+
+endif
+EXTRA_DIST += strchrnul.c strchrnul.valgrind
+
+EXTRA_libgnu_a_SOURCES += strchrnul.c
+
+endif
+## end   gnulib module strchrnul
+
 ## begin gnulib module string
 ifeq (,$(OMIT_GNULIB_MODULE_string))
 
diff --git a/lib/sched.in.h b/lib/sched.in.h
new file mode 100644
index 00000000000..4ee9defe82b
--- /dev/null
+++ b/lib/sched.in.h
@@ -0,0 +1,99 @@
+/* A GNU-like <sched.h>.
+   Copyright (C) 2008-2020 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#ifndef _@GUARD_PREFIX@_SCHED_H
+
+#if __GNUC__ >= 3
+@PRAGMA_SYSTEM_HEADER@
+#endif
+@PRAGMA_COLUMNS@
+
+/* The include_next requires a split double-inclusion guard.  */
+#if @HAVE_SCHED_H@
+# if @HAVE_SYS_CDEFS_H@
+#  include <sys/cdefs.h>
+# endif
+# @INCLUDE_NEXT@ @NEXT_SCHED_H@
+#endif
+
+#ifndef _@GUARD_PREFIX@_SCHED_H
+#define _@GUARD_PREFIX@_SCHED_H
+
+/* Get pid_t.
+   This is needed on glibc 2.11 (see
+   glibc bug <https://sourceware.org/bugzilla/show_bug.cgi?id=13198>)
+   and Mac OS X 10.5.  */
+#include <sys/types.h>
+
+#ifdef __KLIBC__
+/* On OS/2 kLIBC, struct sched_param is in spawn.h.  */
+# include <spawn.h>
+#endif
+
+#ifdef __VMS
+/* On OpenVMS, struct sched_param is in <pthread.h>.  */
+# include <pthread.h>
+#endif
+
+/* The definitions of _GL_FUNCDECL_RPL etc. are copied here.  */
+
+/* The definition of _GL_WARN_ON_USE is copied here.  */
+
+#if !@HAVE_STRUCT_SCHED_PARAM@
+
+# if !GNULIB_defined_struct_sched_param
+struct sched_param
+{
+  int sched_priority;
+};
+#  define GNULIB_defined_struct_sched_param 1
+# endif
+
+#endif
+
+#if !(defined SCHED_FIFO && defined SCHED_RR && defined SCHED_OTHER)
+# define SCHED_FIFO   1
+# define SCHED_RR     2
+# define SCHED_OTHER  0
+#endif
+
+#if @GNULIB_SCHED_YIELD@
+# if @REPLACE_SCHED_YIELD@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef sched_yield
+#   define sched_yield rpl_sched_yield
+#  endif
+_GL_FUNCDECL_RPL (sched_yield, int, (void));
+_GL_CXXALIAS_RPL (sched_yield, int, (void));
+# else
+#  if !@HAVE_SCHED_YIELD@
+_GL_FUNCDECL_SYS (sched_yield, int, (void));
+#  endif
+_GL_CXXALIAS_SYS (sched_yield, int, (void));
+# endif
+# if __GLIBC__ >= 2
+_GL_CXXALIASWARN (sched_yield);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef sched_yield
+# if HAVE_RAW_DECL_SCHED_YIELD
+_GL_WARN_ON_USE (sched_yield, "sched_yield is not portable - "
+                 "use gnulib module sched_yield for portability");
+# endif
+#endif
+
+#endif /* _@GUARD_PREFIX@_SCHED_H */
+#endif /* _@GUARD_PREFIX@_SCHED_H */
diff --git a/lib/spawn.c b/lib/spawn.c
new file mode 100644
index 00000000000..b658453a10f
--- /dev/null
+++ b/lib/spawn.c
@@ -0,0 +1,34 @@
+/* Copyright (C) 2000, 2009-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+
+#include "spawn_int.h"
+
+/* Spawn a new process executing PATH with the attributes describes in *ATTRP.
+   Before running the process perform the actions described in FILE-ACTIONS. */
+int
+posix_spawn (pid_t *pid, const char *path,
+             const posix_spawn_file_actions_t *file_actions,
+             const posix_spawnattr_t *attrp, char *const argv[],
+             char *const envp[])
+{
+  return __spawni (pid, path, file_actions, attrp,
+                   (const char * const *) argv, (const char * const *) envp, 0);
+}
diff --git a/lib/spawn.in.h b/lib/spawn.in.h
new file mode 100644
index 00000000000..537fac7dbc5
--- /dev/null
+++ b/lib/spawn.in.h
@@ -0,0 +1,974 @@
+/* Definitions for POSIX spawn interface.
+   Copyright (C) 2000, 2003-2004, 2008-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#ifndef _@GUARD_PREFIX@_SPAWN_H
+
+#if __GNUC__ >= 3
+@PRAGMA_SYSTEM_HEADER@
+#endif
+@PRAGMA_COLUMNS@
+
+/* The include_next requires a split double-inclusion guard.  */
+#if @HAVE_SPAWN_H@
+# @INCLUDE_NEXT@ @NEXT_SPAWN_H@
+#endif
+
+#ifndef _@GUARD_PREFIX@_SPAWN_H
+#define _@GUARD_PREFIX@_SPAWN_H
+
+/* Get definitions of 'struct sched_param' and 'sigset_t'.
+   But avoid namespace pollution on glibc systems.  */
+#if !(defined __GLIBC__ && !defined __UCLIBC__)
+# include <sched.h>
+# include <signal.h>
+#endif
+
+#include <sys/types.h>
+
+#ifndef __THROW
+# define __THROW
+#endif
+
+/* For plain 'restrict', use glibc's __restrict if defined.
+   Otherwise, GCC 2.95 and later have "__restrict"; C99 compilers have
+   "restrict", and "configure" may have defined "restrict".
+   Other compilers use __restrict, __restrict__, and _Restrict, and
+   'configure' might #define 'restrict' to those words, so pick a
+   different name.  */
+#ifndef _Restrict_
+# if defined __restrict \
+     || 2 < __GNUC__ + (95 <= __GNUC_MINOR__) \
+     || __clang_major__ >= 3
+#  define _Restrict_ __restrict
+# elif 199901L <= __STDC_VERSION__ || defined restrict
+#  define _Restrict_ restrict
+# else
+#  define _Restrict_
+# endif
+#endif
+/* For the ISO C99 syntax
+     array_name[restrict]
+   use glibc's __restrict_arr if available.
+   Otherwise, GCC 3.1 and clang support this syntax (but not in C++ mode).
+   Other ISO C99 compilers support it as well.  */
+#ifndef _Restrict_arr_
+# ifdef __restrict_arr
+#  define _Restrict_arr_ __restrict_arr
+# elif ((199901L <= __STDC_VERSION__ \
+         || 3 < __GNUC__ + (1 <= __GNUC_MINOR__) \
+         || __clang_major__ >= 3) \
+        && !defined __cplusplus)
+#  define _Restrict_arr_ _Restrict_
+# else
+#  define _Restrict_arr_
+# endif
+#endif
+
+/* The definitions of _GL_FUNCDECL_RPL etc. are copied here.  */
+
+/* The definition of _GL_ARG_NONNULL is copied here.  */
+
+/* The definition of _GL_WARN_ON_USE is copied here.  */
+
+
+/* Data structure to contain attributes for thread creation.  */
+#if @REPLACE_POSIX_SPAWN@ || (@HAVE_POSIX_SPAWNATTR_T@ && !@HAVE_POSIX_SPAWN@)
+# define posix_spawnattr_t rpl_posix_spawnattr_t
+#endif
+#if @REPLACE_POSIX_SPAWN@ || !@HAVE_POSIX_SPAWNATTR_T@ || !@HAVE_POSIX_SPAWN@
+# if !GNULIB_defined_posix_spawnattr_t
+typedef struct
+{
+  short int _flags;
+  pid_t _pgrp;
+  sigset_t _sd;
+  sigset_t _ss;
+  struct sched_param _sp;
+  int _policy;
+  int __pad[16];
+} posix_spawnattr_t;
+#  define GNULIB_defined_posix_spawnattr_t 1
+# endif
+#endif
+
+
+/* Data structure to contain information about the actions to be
+   performed in the new process with respect to file descriptors.  */
+#if @REPLACE_POSIX_SPAWN@ || (@HAVE_POSIX_SPAWN_FILE_ACTIONS_T@ && !@HAVE_POSIX_SPAWN@)
+# define posix_spawn_file_actions_t rpl_posix_spawn_file_actions_t
+#endif
+#if @REPLACE_POSIX_SPAWN@ || !@HAVE_POSIX_SPAWN_FILE_ACTIONS_T@ || !@HAVE_POSIX_SPAWN@
+# if !GNULIB_defined_posix_spawn_file_actions_t
+typedef struct
+{
+  int _allocated;
+  int _used;
+  struct __spawn_action *_actions;
+  int __pad[16];
+} posix_spawn_file_actions_t;
+#  define GNULIB_defined_posix_spawn_file_actions_t 1
+# endif
+#endif
+
+
+/* Flags to be set in the 'posix_spawnattr_t'.  */
+#if @HAVE_POSIX_SPAWN@
+/* Use the values from the system, but provide the missing ones.  */
+# ifndef POSIX_SPAWN_SETSCHEDPARAM
+#  define POSIX_SPAWN_SETSCHEDPARAM 0
+# endif
+# ifndef POSIX_SPAWN_SETSCHEDULER
+#  define POSIX_SPAWN_SETSCHEDULER 0
+# endif
+#else
+# if @REPLACE_POSIX_SPAWN@
+/* Use the values from the system, for better compatibility.  */
+/* But this implementation does not support AIX extensions.  */
+#  undef POSIX_SPAWN_FORK_HANDLERS
+# else
+#  define POSIX_SPAWN_RESETIDS           0x01
+#  define POSIX_SPAWN_SETPGROUP          0x02
+#  define POSIX_SPAWN_SETSIGDEF          0x04
+#  define POSIX_SPAWN_SETSIGMASK         0x08
+#  define POSIX_SPAWN_SETSCHEDPARAM      0x10
+#  define POSIX_SPAWN_SETSCHEDULER       0x20
+# endif
+#endif
+/* A GNU extension.  Use the next free bit position.  */
+#ifndef POSIX_SPAWN_USEVFORK
+# define POSIX_SPAWN_USEVFORK \
+  ((POSIX_SPAWN_RESETIDS | (POSIX_SPAWN_RESETIDS - 1)                     \
+    | POSIX_SPAWN_SETPGROUP | (POSIX_SPAWN_SETPGROUP - 1)                 \
+    | POSIX_SPAWN_SETSIGDEF | (POSIX_SPAWN_SETSIGDEF - 1)                 \
+    | POSIX_SPAWN_SETSIGMASK | (POSIX_SPAWN_SETSIGMASK - 1)               \
+    | POSIX_SPAWN_SETSCHEDPARAM                                           \
+    | (POSIX_SPAWN_SETSCHEDPARAM > 0 ? POSIX_SPAWN_SETSCHEDPARAM - 1 : 0) \
+    | POSIX_SPAWN_SETSCHEDULER                                            \
+    | (POSIX_SPAWN_SETSCHEDULER > 0 ? POSIX_SPAWN_SETSCHEDULER - 1 : 0))  \
+   + 1)
+#endif
+#if !GNULIB_defined_verify_POSIX_SPAWN_USEVFORK_no_overlap
+typedef int verify_POSIX_SPAWN_USEVFORK_no_overlap
+            [(((POSIX_SPAWN_RESETIDS | POSIX_SPAWN_SETPGROUP
+                | POSIX_SPAWN_SETSIGDEF | POSIX_SPAWN_SETSIGMASK
+                | POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER)
+               & POSIX_SPAWN_USEVFORK)
+              == 0)
+             ? 1 : -1];
+# define GNULIB_defined_verify_POSIX_SPAWN_USEVFORK_no_overlap 1
+#endif
+
+
+#if @GNULIB_POSIX_SPAWN@
+/* Spawn a new process executing PATH with the attributes describes in *ATTRP.
+   Before running the process perform the actions described in FILE-ACTIONS.
+
+   This function is a possible cancellation points and therefore not
+   marked with __THROW. */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawn rpl_posix_spawn
+#  endif
+_GL_FUNCDECL_RPL (posix_spawn, int,
+                  (pid_t *_Restrict_ __pid,
+                   const char *_Restrict_ __path,
+                   const posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   const posix_spawnattr_t *_Restrict_ __attrp,
+                   char *const argv[_Restrict_arr_],
+                   char *const envp[_Restrict_arr_])
+                  _GL_ARG_NONNULL ((2, 5, 6)));
+_GL_CXXALIAS_RPL (posix_spawn, int,
+                  (pid_t *_Restrict_ __pid,
+                   const char *_Restrict_ __path,
+                   const posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   const posix_spawnattr_t *_Restrict_ __attrp,
+                   char *const argv[_Restrict_arr_],
+                   char *const envp[_Restrict_arr_]));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawn, int,
+                  (pid_t *_Restrict_ __pid,
+                   const char *_Restrict_ __path,
+                   const posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   const posix_spawnattr_t *_Restrict_ __attrp,
+                   char *const argv[_Restrict_arr_],
+                   char *const envp[_Restrict_arr_])
+                  _GL_ARG_NONNULL ((2, 5, 6)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawn, int,
+                  (pid_t *_Restrict_ __pid,
+                   const char *_Restrict_ __path,
+                   const posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   const posix_spawnattr_t *_Restrict_ __attrp,
+                   char *const argv[_Restrict_arr_],
+                   char *const envp[_Restrict_arr_]));
+# endif
+_GL_CXXALIASWARN (posix_spawn);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawn
+# if HAVE_RAW_DECL_POSIX_SPAWN
+_GL_WARN_ON_USE (posix_spawn, "posix_spawn is unportable - "
+                 "use gnulib module posix_spawn for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNP@
+/* Similar to 'posix_spawn' but search for FILE in the PATH.
+
+   This function is a possible cancellation points and therefore not
+   marked with __THROW.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnp rpl_posix_spawnp
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnp, int,
+                  (pid_t *__pid, const char *__file,
+                   const posix_spawn_file_actions_t *__file_actions,
+                   const posix_spawnattr_t *__attrp,
+                   char *const argv[], char *const envp[])
+                  _GL_ARG_NONNULL ((2, 5, 6)));
+_GL_CXXALIAS_RPL (posix_spawnp, int,
+                  (pid_t *__pid, const char *__file,
+                   const posix_spawn_file_actions_t *__file_actions,
+                   const posix_spawnattr_t *__attrp,
+                   char *const argv[], char *const envp[]));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawnp, int,
+                  (pid_t *__pid, const char *__file,
+                   const posix_spawn_file_actions_t *__file_actions,
+                   const posix_spawnattr_t *__attrp,
+                   char *const argv[], char *const envp[])
+                  _GL_ARG_NONNULL ((2, 5, 6)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnp, int,
+                  (pid_t *__pid, const char *__file,
+                   const posix_spawn_file_actions_t *__file_actions,
+                   const posix_spawnattr_t *__attrp,
+                   char *const argv[], char *const envp[]));
+# endif
+_GL_CXXALIASWARN (posix_spawnp);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnp
+# if HAVE_RAW_DECL_POSIX_SPAWNP
+_GL_WARN_ON_USE (posix_spawnp, "posix_spawnp is unportable - "
+                 "use gnulib module posix_spawnp for portability");
+# endif
+#endif
+
+
+#if @GNULIB_POSIX_SPAWNATTR_INIT@
+/* Initialize data structure with attributes for 'spawn' to default values.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_init rpl_posix_spawnattr_init
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_init, int, (posix_spawnattr_t *__attr)
+                                             __THROW _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (posix_spawnattr_init, int, (posix_spawnattr_t *__attr));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawnattr_init, int, (posix_spawnattr_t *__attr)
+                                             __THROW _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_init, int, (posix_spawnattr_t *__attr));
+# endif
+_GL_CXXALIASWARN (posix_spawnattr_init);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_init
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_INIT
+_GL_WARN_ON_USE (posix_spawnattr_init, "posix_spawnattr_init is unportable - "
+                 "use gnulib module posix_spawnattr_init for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_DESTROY@
+/* Free resources associated with ATTR.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_destroy rpl_posix_spawnattr_destroy
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_destroy, int, (posix_spawnattr_t *__attr)
+                                                __THROW _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (posix_spawnattr_destroy, int, (posix_spawnattr_t *__attr));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawnattr_destroy, int, (posix_spawnattr_t *__attr)
+                                                __THROW _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_destroy, int, (posix_spawnattr_t *__attr));
+# endif
+_GL_CXXALIASWARN (posix_spawnattr_destroy);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_destroy
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_DESTROY
+_GL_WARN_ON_USE (posix_spawnattr_destroy,
+                 "posix_spawnattr_destroy is unportable - "
+                 "use gnulib module posix_spawnattr_destroy for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_GETSIGDEFAULT@
+/* Store signal mask for signals with default handling from ATTR in
+   SIGDEFAULT.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_getsigdefault rpl_posix_spawnattr_getsigdefault
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_getsigdefault, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   sigset_t *_Restrict_ __sigdefault)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (posix_spawnattr_getsigdefault, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   sigset_t *_Restrict_ __sigdefault));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawnattr_getsigdefault, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   sigset_t *_Restrict_ __sigdefault)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_getsigdefault, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   sigset_t *_Restrict_ __sigdefault));
+# endif
+_GL_CXXALIASWARN (posix_spawnattr_getsigdefault);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_getsigdefault
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_GETSIGDEFAULT
+_GL_WARN_ON_USE (posix_spawnattr_getsigdefault,
+                 "posix_spawnattr_getsigdefault is unportable - "
+                 "use gnulib module posix_spawnattr_getsigdefault for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_SETSIGDEFAULT@
+/* Set signal mask for signals with default handling in ATTR to SIGDEFAULT.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_setsigdefault rpl_posix_spawnattr_setsigdefault
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_setsigdefault, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const sigset_t *_Restrict_ __sigdefault)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (posix_spawnattr_setsigdefault, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const sigset_t *_Restrict_ __sigdefault));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawnattr_setsigdefault, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const sigset_t *_Restrict_ __sigdefault)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_setsigdefault, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const sigset_t *_Restrict_ __sigdefault));
+# endif
+_GL_CXXALIASWARN (posix_spawnattr_setsigdefault);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_setsigdefault
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_SETSIGDEFAULT
+_GL_WARN_ON_USE (posix_spawnattr_setsigdefault,
+                 "posix_spawnattr_setsigdefault is unportable - "
+                 "use gnulib module posix_spawnattr_setsigdefault for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_GETSIGMASK@
+/* Store signal mask for the new process from ATTR in SIGMASK.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_getsigmask rpl_posix_spawnattr_getsigmask
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_getsigmask, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   sigset_t *_Restrict_ __sigmask)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (posix_spawnattr_getsigmask, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   sigset_t *_Restrict_ __sigmask));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawnattr_getsigmask, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   sigset_t *_Restrict_ __sigmask)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_getsigmask, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   sigset_t *_Restrict_ __sigmask));
+# endif
+_GL_CXXALIASWARN (posix_spawnattr_getsigmask);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_getsigmask
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_GETSIGMASK
+_GL_WARN_ON_USE (posix_spawnattr_getsigmask,
+                 "posix_spawnattr_getsigmask is unportable - "
+                 "use gnulib module posix_spawnattr_getsigmask for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_SETSIGMASK@
+/* Set signal mask for the new process in ATTR to SIGMASK.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_setsigmask rpl_posix_spawnattr_setsigmask
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_setsigmask, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const sigset_t *_Restrict_ __sigmask)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (posix_spawnattr_setsigmask, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const sigset_t *_Restrict_ __sigmask));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawnattr_setsigmask, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const sigset_t *_Restrict_ __sigmask)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_setsigmask, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const sigset_t *_Restrict_ __sigmask));
+# endif
+_GL_CXXALIASWARN (posix_spawnattr_setsigmask);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_setsigmask
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_SETSIGMASK
+_GL_WARN_ON_USE (posix_spawnattr_setsigmask,
+                 "posix_spawnattr_setsigmask is unportable - "
+                 "use gnulib module posix_spawnattr_setsigmask for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_GETFLAGS@
+/* Get flag word from the attribute structure.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_getflags rpl_posix_spawnattr_getflags
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_getflags, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   short int *_Restrict_ __flags)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (posix_spawnattr_getflags, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   short int *_Restrict_ __flags));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawnattr_getflags, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   short int *_Restrict_ __flags)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_getflags, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   short int *_Restrict_ __flags));
+# endif
+_GL_CXXALIASWARN (posix_spawnattr_getflags);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_getflags
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_GETFLAGS
+_GL_WARN_ON_USE (posix_spawnattr_getflags,
+                 "posix_spawnattr_getflags is unportable - "
+                 "use gnulib module posix_spawnattr_getflags for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_SETFLAGS@
+/* Store flags in the attribute structure.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_setflags rpl_posix_spawnattr_setflags
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_setflags, int,
+                  (posix_spawnattr_t *__attr, short int __flags)
+                  __THROW _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (posix_spawnattr_setflags, int,
+                  (posix_spawnattr_t *__attr, short int __flags));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawnattr_setflags, int,
+                  (posix_spawnattr_t *__attr, short int __flags)
+                  __THROW _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_setflags, int,
+                  (posix_spawnattr_t *__attr, short int __flags));
+# endif
+_GL_CXXALIASWARN (posix_spawnattr_setflags);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_setflags
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_SETFLAGS
+_GL_WARN_ON_USE (posix_spawnattr_setflags,
+                 "posix_spawnattr_setflags is unportable - "
+                 "use gnulib module posix_spawnattr_setflags for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_GETPGROUP@
+/* Get process group ID from the attribute structure.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_getpgroup rpl_posix_spawnattr_getpgroup
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_getpgroup, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   pid_t *_Restrict_ __pgroup)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (posix_spawnattr_getpgroup, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   pid_t *_Restrict_ __pgroup));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawnattr_getpgroup, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   pid_t *_Restrict_ __pgroup)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_getpgroup, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   pid_t *_Restrict_ __pgroup));
+# endif
+_GL_CXXALIASWARN (posix_spawnattr_getpgroup);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_getpgroup
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_GETPGROUP
+_GL_WARN_ON_USE (posix_spawnattr_getpgroup,
+                 "posix_spawnattr_getpgroup is unportable - "
+                 "use gnulib module posix_spawnattr_getpgroup for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_SETPGROUP@
+/* Store process group ID in the attribute structure.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_setpgroup rpl_posix_spawnattr_setpgroup
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_setpgroup, int,
+                  (posix_spawnattr_t *__attr, pid_t __pgroup)
+                  __THROW _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (posix_spawnattr_setpgroup, int,
+                  (posix_spawnattr_t *__attr, pid_t __pgroup));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawnattr_setpgroup, int,
+                  (posix_spawnattr_t *__attr, pid_t __pgroup)
+                  __THROW _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_setpgroup, int,
+                  (posix_spawnattr_t *__attr, pid_t __pgroup));
+# endif
+_GL_CXXALIASWARN (posix_spawnattr_setpgroup);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_setpgroup
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_SETPGROUP
+_GL_WARN_ON_USE (posix_spawnattr_setpgroup,
+                 "posix_spawnattr_setpgroup is unportable - "
+                 "use gnulib module posix_spawnattr_setpgroup for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_GETSCHEDPOLICY@
+/* Get scheduling policy from the attribute structure.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_getschedpolicy rpl_posix_spawnattr_getschedpolicy
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_getschedpolicy, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   int *_Restrict_ __schedpolicy)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (posix_spawnattr_getschedpolicy, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   int *_Restrict_ __schedpolicy));
+# else
+#  if !@HAVE_POSIX_SPAWN@ || POSIX_SPAWN_SETSCHEDULER == 0
+_GL_FUNCDECL_SYS (posix_spawnattr_getschedpolicy, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   int *_Restrict_ __schedpolicy)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_getschedpolicy, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   int *_Restrict_ __schedpolicy));
+# endif
+# if __GLIBC__ >= 2
+_GL_CXXALIASWARN (posix_spawnattr_getschedpolicy);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_getschedpolicy
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_GETSCHEDPOLICY
+_GL_WARN_ON_USE (posix_spawnattr_getschedpolicy,
+                 "posix_spawnattr_getschedpolicy is unportable - "
+                 "use gnulib module posix_spawnattr_getschedpolicy for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_SETSCHEDPOLICY@
+/* Store scheduling policy in the attribute structure.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_setschedpolicy rpl_posix_spawnattr_setschedpolicy
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_setschedpolicy, int,
+                  (posix_spawnattr_t *__attr, int __schedpolicy)
+                  __THROW _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (posix_spawnattr_setschedpolicy, int,
+                  (posix_spawnattr_t *__attr, int __schedpolicy));
+# else
+#  if !@HAVE_POSIX_SPAWN@ || POSIX_SPAWN_SETSCHEDULER == 0
+_GL_FUNCDECL_SYS (posix_spawnattr_setschedpolicy, int,
+                  (posix_spawnattr_t *__attr, int __schedpolicy)
+                  __THROW _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_setschedpolicy, int,
+                  (posix_spawnattr_t *__attr, int __schedpolicy));
+# endif
+# if __GLIBC__ >= 2
+_GL_CXXALIASWARN (posix_spawnattr_setschedpolicy);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_setschedpolicy
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_SETSCHEDPOLICY
+_GL_WARN_ON_USE (posix_spawnattr_setschedpolicy,
+                 "posix_spawnattr_setschedpolicy is unportable - "
+                 "use gnulib module posix_spawnattr_setschedpolicy for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_GETSCHEDPARAM@
+/* Get scheduling parameters from the attribute structure.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_getschedparam rpl_posix_spawnattr_getschedparam
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_getschedparam, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   struct sched_param *_Restrict_ __schedparam)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (posix_spawnattr_getschedparam, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   struct sched_param *_Restrict_ __schedparam));
+# else
+#  if !@HAVE_POSIX_SPAWN@ || POSIX_SPAWN_SETSCHEDPARAM == 0
+_GL_FUNCDECL_SYS (posix_spawnattr_getschedparam, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   struct sched_param *_Restrict_ __schedparam)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_getschedparam, int,
+                  (const posix_spawnattr_t *_Restrict_ __attr,
+                   struct sched_param *_Restrict_ __schedparam));
+# endif
+# if __GLIBC__ >= 2
+_GL_CXXALIASWARN (posix_spawnattr_getschedparam);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_getschedparam
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_GETSCHEDPARAM
+_GL_WARN_ON_USE (posix_spawnattr_getschedparam,
+                 "posix_spawnattr_getschedparam is unportable - "
+                 "use gnulib module posix_spawnattr_getschedparam for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWNATTR_SETSCHEDPARAM@
+/* Store scheduling parameters in the attribute structure.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawnattr_setschedparam rpl_posix_spawnattr_setschedparam
+#  endif
+_GL_FUNCDECL_RPL (posix_spawnattr_setschedparam, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const struct sched_param *_Restrict_ __schedparam)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (posix_spawnattr_setschedparam, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const struct sched_param *_Restrict_ __schedparam));
+# else
+#  if !@HAVE_POSIX_SPAWN@ || POSIX_SPAWN_SETSCHEDPARAM == 0
+_GL_FUNCDECL_SYS (posix_spawnattr_setschedparam, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const struct sched_param *_Restrict_ __schedparam)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawnattr_setschedparam, int,
+                  (posix_spawnattr_t *_Restrict_ __attr,
+                   const struct sched_param *_Restrict_ __schedparam));
+# endif
+# if __GLIBC__ >= 2
+_GL_CXXALIASWARN (posix_spawnattr_setschedparam);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawnattr_setschedparam
+# if HAVE_RAW_DECL_POSIX_SPAWNATTR_SETSCHEDPARAM
+_GL_WARN_ON_USE (posix_spawnattr_setschedparam,
+                 "posix_spawnattr_setschedparam is unportable - "
+                 "use gnulib module posix_spawnattr_setschedparam for portability");
+# endif
+#endif
+
+
+#if @GNULIB_POSIX_SPAWN_FILE_ACTIONS_INIT@
+/* Initialize data structure for file attribute for 'spawn' call.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawn_file_actions_init rpl_posix_spawn_file_actions_init
+#  endif
+_GL_FUNCDECL_RPL (posix_spawn_file_actions_init, int,
+                  (posix_spawn_file_actions_t *__file_actions)
+                  __THROW _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (posix_spawn_file_actions_init, int,
+                  (posix_spawn_file_actions_t *__file_actions));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawn_file_actions_init, int,
+                  (posix_spawn_file_actions_t *__file_actions)
+                  __THROW _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawn_file_actions_init, int,
+                  (posix_spawn_file_actions_t *__file_actions));
+# endif
+_GL_CXXALIASWARN (posix_spawn_file_actions_init);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawn_file_actions_init
+# if HAVE_RAW_DECL_POSIX_SPAWN_FILE_ACTIONS_INIT
+_GL_WARN_ON_USE (posix_spawn_file_actions_init,
+                 "posix_spawn_file_actions_init is unportable - "
+                 "use gnulib module posix_spawn_file_actions_init for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWN_FILE_ACTIONS_DESTROY@
+/* Free resources associated with FILE-ACTIONS.  */
+# if @REPLACE_POSIX_SPAWN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawn_file_actions_destroy rpl_posix_spawn_file_actions_destroy
+#  endif
+_GL_FUNCDECL_RPL (posix_spawn_file_actions_destroy, int,
+                  (posix_spawn_file_actions_t *__file_actions)
+                  __THROW _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (posix_spawn_file_actions_destroy, int,
+                  (posix_spawn_file_actions_t *__file_actions));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawn_file_actions_destroy, int,
+                  (posix_spawn_file_actions_t *__file_actions)
+                  __THROW _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawn_file_actions_destroy, int,
+                  (posix_spawn_file_actions_t *__file_actions));
+# endif
+_GL_CXXALIASWARN (posix_spawn_file_actions_destroy);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawn_file_actions_destroy
+# if HAVE_RAW_DECL_POSIX_SPAWN_FILE_ACTIONS_DESTROY
+_GL_WARN_ON_USE (posix_spawn_file_actions_destroy,
+                 "posix_spawn_file_actions_destroy is unportable - "
+                 "use gnulib module posix_spawn_file_actions_destroy for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN@
+/* Add an action to FILE-ACTIONS which tells the implementation to call
+   'open' for the given file during the 'spawn' call.  */
+# if @REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawn_file_actions_addopen rpl_posix_spawn_file_actions_addopen
+#  endif
+_GL_FUNCDECL_RPL (posix_spawn_file_actions_addopen, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   int __fd,
+                   const char *_Restrict_ __path, int __oflag, mode_t __mode)
+                  __THROW _GL_ARG_NONNULL ((1, 3)));
+_GL_CXXALIAS_RPL (posix_spawn_file_actions_addopen, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   int __fd,
+                   const char *_Restrict_ __path, int __oflag, mode_t __mode));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawn_file_actions_addopen, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   int __fd,
+                   const char *_Restrict_ __path, int __oflag, mode_t __mode)
+                  __THROW _GL_ARG_NONNULL ((1, 3)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawn_file_actions_addopen, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   int __fd,
+                   const char *_Restrict_ __path, int __oflag, mode_t __mode));
+# endif
+# if __GLIBC__ >= 2
+_GL_CXXALIASWARN (posix_spawn_file_actions_addopen);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawn_file_actions_addopen
+# if HAVE_RAW_DECL_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN
+_GL_WARN_ON_USE (posix_spawn_file_actions_addopen,
+                 "posix_spawn_file_actions_addopen is unportable - "
+                 "use gnulib module posix_spawn_file_actions_addopen for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE@
+/* Add an action to FILE-ACTIONS which tells the implementation to call
+   'close' for the given file descriptor during the 'spawn' call.  */
+# if @REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawn_file_actions_addclose rpl_posix_spawn_file_actions_addclose
+#  endif
+_GL_FUNCDECL_RPL (posix_spawn_file_actions_addclose, int,
+                  (posix_spawn_file_actions_t *__file_actions, int __fd)
+                  __THROW _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (posix_spawn_file_actions_addclose, int,
+                  (posix_spawn_file_actions_t *__file_actions, int __fd));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawn_file_actions_addclose, int,
+                  (posix_spawn_file_actions_t *__file_actions, int __fd)
+                  __THROW _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawn_file_actions_addclose, int,
+                  (posix_spawn_file_actions_t *__file_actions, int __fd));
+# endif
+# if __GLIBC__ >= 2
+_GL_CXXALIASWARN (posix_spawn_file_actions_addclose);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawn_file_actions_addclose
+# if HAVE_RAW_DECL_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE
+_GL_WARN_ON_USE (posix_spawn_file_actions_addclose,
+                 "posix_spawn_file_actions_addclose is unportable - "
+                 "use gnulib module posix_spawn_file_actions_addclose for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2@
+/* Add an action to FILE-ACTIONS which tells the implementation to call
+   'dup2' for the given file descriptors during the 'spawn' call.  */
+# if @REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawn_file_actions_adddup2 rpl_posix_spawn_file_actions_adddup2
+#  endif
+_GL_FUNCDECL_RPL (posix_spawn_file_actions_adddup2, int,
+                  (posix_spawn_file_actions_t *__file_actions,
+                   int __fd, int __newfd)
+                  __THROW _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (posix_spawn_file_actions_adddup2, int,
+                  (posix_spawn_file_actions_t *__file_actions,
+                   int __fd, int __newfd));
+# else
+#  if !@HAVE_POSIX_SPAWN@
+_GL_FUNCDECL_SYS (posix_spawn_file_actions_adddup2, int,
+                  (posix_spawn_file_actions_t *__file_actions,
+                   int __fd, int __newfd)
+                  __THROW _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawn_file_actions_adddup2, int,
+                  (posix_spawn_file_actions_t *__file_actions,
+                   int __fd, int __newfd));
+# endif
+# if __GLIBC__ >= 2
+_GL_CXXALIASWARN (posix_spawn_file_actions_adddup2);
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawn_file_actions_adddup2
+# if HAVE_RAW_DECL_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2
+_GL_WARN_ON_USE (posix_spawn_file_actions_adddup2,
+                 "posix_spawn_file_actions_adddup2 is unportable - "
+                 "use gnulib module posix_spawn_file_actions_adddup2 for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR@
+/* Add an action to FILE-ACTIONS which tells the implementation to call
+   'chdir' to the given directory during the 'spawn' call.  */
+# if @REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawn_file_actions_addchdir rpl_posix_spawn_file_actions_addchdir
+#  endif
+_GL_FUNCDECL_RPL (posix_spawn_file_actions_addchdir, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   const char *_Restrict_ __path)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+_GL_CXXALIAS_RPL (posix_spawn_file_actions_addchdir, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   const char *_Restrict_ __path));
+# else
+#  if !@HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR@
+_GL_FUNCDECL_SYS (posix_spawn_file_actions_addchdir, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   const char *_Restrict_ __path)
+                  __THROW _GL_ARG_NONNULL ((1, 2)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawn_file_actions_addchdir, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   const char *_Restrict_ __path));
+# endif
+_GL_CXXALIASWARN (posix_spawn_file_actions_addchdir);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawn_file_actions_addchdir
+# if HAVE_RAW_DECL_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR
+_GL_WARN_ON_USE (posix_spawn_file_actions_addchdir,
+                 "posix_spawn_file_actions_addchdir is unportable - "
+                 "use gnulib module posix_spawn_file_actions_addchdir for portability");
+# endif
+#endif
+
+#if @GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR@
+/* Add an action to FILE-ACTIONS which tells the implementation to call
+   'fchdir' to the given directory during the 'spawn' call.  */
+# if @REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   define posix_spawn_file_actions_addfchdir rpl_posix_spawn_file_actions_addfchdir
+#  endif
+_GL_FUNCDECL_RPL (posix_spawn_file_actions_addfchdir, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   int __fd)
+                  __THROW _GL_ARG_NONNULL ((1)));
+_GL_CXXALIAS_RPL (posix_spawn_file_actions_addfchdir, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   int __fd));
+# else
+#  if !@HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR@
+_GL_FUNCDECL_SYS (posix_spawn_file_actions_addfchdir, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   int __fd)
+                  __THROW _GL_ARG_NONNULL ((1)));
+#  endif
+_GL_CXXALIAS_SYS (posix_spawn_file_actions_addfchdir, int,
+                  (posix_spawn_file_actions_t *_Restrict_ __file_actions,
+                   int __fd));
+# endif
+_GL_CXXALIASWARN (posix_spawn_file_actions_addfchdir);
+#elif defined GNULIB_POSIXCHECK
+# undef posix_spawn_file_actions_addfchdir
+# if HAVE_RAW_DECL_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR
+_GL_WARN_ON_USE (posix_spawn_file_actions_addfchdir,
+                 "posix_spawn_file_actions_addfchdir is unportable - "
+                 "use gnulib module posix_spawn_file_actions_addfchdir for portability");
+# endif
+#endif
+
+
+#endif /* _@GUARD_PREFIX@_SPAWN_H */
+#endif /* _@GUARD_PREFIX@_SPAWN_H */
diff --git a/lib/spawn_faction_addchdir.c b/lib/spawn_faction_addchdir.c
new file mode 100644
index 00000000000..8fb6cb0f7d2
--- /dev/null
+++ b/lib/spawn_faction_addchdir.c
@@ -0,0 +1,70 @@
+/* Copyright (C) 2018-2020 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#if REPLACE_POSIX_SPAWN
+# include "spawn_int.h"
+#endif
+
+/* Add an action to FILE-ACTIONS which tells the implementation to call
+   'chdir' to the given directory during the 'spawn' call.  */
+int
+posix_spawn_file_actions_addchdir (posix_spawn_file_actions_t *file_actions,
+                                   const char *path)
+#undef posix_spawn_file_actions_addchdir
+{
+#if !REPLACE_POSIX_SPAWN
+  return posix_spawn_file_actions_addchdir_np (file_actions, path);
+#else
+  {
+    /* Copy PATH, because the caller may free it before calling posix_spawn()
+       or posix_spawnp().  */
+    char *path_copy = strdup (path);
+    if (path_copy == NULL)
+      return ENOMEM;
+
+    /* Allocate more memory if needed.  */
+    if (file_actions->_used == file_actions->_allocated
+        && __posix_spawn_file_actions_realloc (file_actions) != 0)
+      {
+        /* This can only mean we ran out of memory.  */
+        free (path_copy);
+        return ENOMEM;
+      }
+
+    {
+      struct __spawn_action *rec;
+
+      /* Add the new value.  */
+      rec = &file_actions->_actions[file_actions->_used];
+      rec->tag = spawn_do_chdir;
+      rec->action.chdir_action.path = path_copy;
+
+      /* Account for the new entry.  */
+      ++file_actions->_used;
+
+      return 0;
+    }
+  }
+#endif
+}
diff --git a/lib/spawn_faction_adddup2.c b/lib/spawn_faction_adddup2.c
new file mode 100644
index 00000000000..c00b0b49668
--- /dev/null
+++ b/lib/spawn_faction_adddup2.c
@@ -0,0 +1,70 @@
+/* Copyright (C) 2000, 2009-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+
+#include <errno.h>
+#include <unistd.h>
+
+#if !_LIBC
+# define __sysconf(open_max) getdtablesize ()
+#endif
+
+#if REPLACE_POSIX_SPAWN
+# include "spawn_int.h"
+#endif
+
+/* Add an action to FILE-ACTIONS which tells the implementation to call
+   'dup2' for the given file descriptors during the 'spawn' call.  */
+int
+posix_spawn_file_actions_adddup2 (posix_spawn_file_actions_t *file_actions,
+                                  int fd, int newfd)
+#undef posix_spawn_file_actions_adddup2
+{
+  int maxfd = __sysconf (_SC_OPEN_MAX);
+
+  /* Test for the validity of the file descriptor.  */
+  if (fd < 0 || newfd < 0 || fd >= maxfd || newfd >= maxfd)
+    return EBADF;
+
+#if !REPLACE_POSIX_SPAWN
+  return posix_spawn_file_actions_adddup2 (file_actions, fd, newfd);
+#else
+  /* Allocate more memory if needed.  */
+  if (file_actions->_used == file_actions->_allocated
+      && __posix_spawn_file_actions_realloc (file_actions) != 0)
+    /* This can only mean we ran out of memory.  */
+    return ENOMEM;
+
+  {
+    struct __spawn_action *rec;
+
+    /* Add the new value.  */
+    rec = &file_actions->_actions[file_actions->_used];
+    rec->tag = spawn_do_dup2;
+    rec->action.dup2_action.fd = fd;
+    rec->action.dup2_action.newfd = newfd;
+
+    /* Account for the new entry.  */
+    ++file_actions->_used;
+
+    return 0;
+  }
+#endif
+}
diff --git a/lib/spawn_faction_destroy.c b/lib/spawn_faction_destroy.c
new file mode 100644
index 00000000000..e9985f4a0d4
--- /dev/null
+++ b/lib/spawn_faction_destroy.c
@@ -0,0 +1,61 @@
+/* Copyright (C) 2000, 2009-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+
+#include <stdlib.h>
+
+#if REPLACE_POSIX_SPAWN
+# include "spawn_int.h"
+#endif
+
+/* Initialize data structure for file attribute for 'spawn' call.  */
+int
+posix_spawn_file_actions_destroy (posix_spawn_file_actions_t *file_actions)
+#undef posix_spawn_file_actions_destroy
+{
+#if !REPLACE_POSIX_SPAWN
+  return posix_spawn_file_actions_destroy (file_actions);
+#else
+  int i;
+
+  /* Free the paths in the open actions.  */
+  for (i = 0; i < file_actions->_used; ++i)
+    {
+      struct __spawn_action *sa = &file_actions->_actions[i];
+      switch (sa->tag)
+        {
+        case spawn_do_open:
+          free (sa->action.open_action.path);
+          break;
+        case spawn_do_chdir:
+          free (sa->action.chdir_action.path);
+          break;
+        default:
+          /* No cleanup required.  */
+          break;
+        }
+    }
+
+  /* Free the array of actions.  */
+  free (file_actions->_actions);
+
+  return 0;
+#endif
+}
diff --git a/lib/spawn_faction_init.c b/lib/spawn_faction_init.c
new file mode 100644
index 00000000000..135605fb8c6
--- /dev/null
+++ b/lib/spawn_faction_init.c
@@ -0,0 +1,56 @@
+/* Copyright (C) 2000, 2009-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "spawn_int.h"
+
+
+/* Function used to increase the size of the allocated array.  This
+   function is called from the 'add'-functions.  */
+int
+__posix_spawn_file_actions_realloc (posix_spawn_file_actions_t *file_actions)
+{
+  int newalloc = file_actions->_allocated + 8;
+  void *newmem = realloc (file_actions->_actions,
+                          newalloc * sizeof (struct __spawn_action));
+
+  if (newmem == NULL)
+    /* Not enough memory.  */
+    return ENOMEM;
+
+  file_actions->_actions = (struct __spawn_action *) newmem;
+  file_actions->_allocated = newalloc;
+
+  return 0;
+}
+
+
+/* Initialize data structure for file attribute for 'spawn' call.  */
+int
+posix_spawn_file_actions_init (posix_spawn_file_actions_t *file_actions)
+{
+  /* Simply clear all the elements.  */
+  memset (file_actions, '\0', sizeof (*file_actions));
+  return 0;
+}
diff --git a/lib/spawn_int.h b/lib/spawn_int.h
new file mode 100644
index 00000000000..60a94ddd55a
--- /dev/null
+++ b/lib/spawn_int.h
@@ -0,0 +1,72 @@
+/* Copyright (C) 2000, 2008-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <sys/types.h>
+
+/* Data structure to contain the action information.  */
+struct __spawn_action
+{
+  enum
+  {
+    spawn_do_close,
+    spawn_do_dup2,
+    spawn_do_open,
+    spawn_do_chdir,
+    spawn_do_fchdir
+  } tag;
+
+  union
+  {
+    struct
+    {
+      int fd;
+    } close_action;
+    struct
+    {
+      int fd;
+      int newfd;
+    } dup2_action;
+    struct
+    {
+      int fd;
+      char *path;
+      int oflag;
+      mode_t mode;
+    } open_action;
+    struct
+    {
+      char *path;
+    } chdir_action;
+    struct
+    {
+      int fd;
+    } fchdir_action;
+  } action;
+};
+
+#if !_LIBC
+# define __posix_spawn_file_actions_realloc gl_posix_spawn_file_actions_realloc
+#endif
+extern int __posix_spawn_file_actions_realloc (posix_spawn_file_actions_t *
+                                               file_actions);
+
+#if !_LIBC
+# define __spawni gl_posix_spawn_internal
+#endif
+extern int __spawni (pid_t *pid, const char *path,
+                     const posix_spawn_file_actions_t *file_actions,
+                     const posix_spawnattr_t *attrp, const char *const argv[],
+                     const char *const envp[], int use_path);
diff --git a/lib/spawnattr_destroy.c b/lib/spawnattr_destroy.c
new file mode 100644
index 00000000000..22a7d5a61a2
--- /dev/null
+++ b/lib/spawnattr_destroy.c
@@ -0,0 +1,28 @@
+/* Copyright (C) 2000, 2009-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+
+/* Initialize data structure for file attribute for 'spawn' call.  */
+int
+posix_spawnattr_destroy (posix_spawnattr_t *attr)
+{
+  /* Nothing to do in the moment.  */
+  return 0;
+}
diff --git a/lib/spawnattr_init.c b/lib/spawnattr_init.c
new file mode 100644
index 00000000000..99674488f81
--- /dev/null
+++ b/lib/spawnattr_init.c
@@ -0,0 +1,33 @@
+/* Copyright (C) 2000, 2009-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+
+#include <string.h>
+
+/* Initialize data structure for file attribute for 'spawn' call.  */
+int
+posix_spawnattr_init (posix_spawnattr_t *attr)
+{
+  /* All elements have to be initialized to the default values which
+     is generally zero.  */
+  memset (attr, '\0', sizeof (*attr));
+
+  return 0;
+}
diff --git a/lib/spawnattr_setdefault.c b/lib/spawnattr_setdefault.c
new file mode 100644
index 00000000000..01c29e94847
--- /dev/null
+++ b/lib/spawnattr_setdefault.c
@@ -0,0 +1,33 @@
+/* Copyright (C) 2000, 2009-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+
+#include <string.h>
+
+/* Set signal mask for signals with default handling in ATTR to SIGDEFAULT.  */
+int
+posix_spawnattr_setsigdefault (posix_spawnattr_t *attr,
+                               const sigset_t *sigdefault)
+{
+  /* Copy the sigset_t data to the user buffer.  */
+  memcpy (&attr->_sd, sigdefault, sizeof (sigset_t));
+
+  return 0;
+}
diff --git a/lib/spawnattr_setflags.c b/lib/spawnattr_setflags.c
new file mode 100644
index 00000000000..084d5bcea4c
--- /dev/null
+++ b/lib/spawnattr_setflags.c
@@ -0,0 +1,45 @@
+/* Copyright (C) 2000, 2004, 2009-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+
+#include <errno.h>
+#include <string.h>
+
+#define ALL_FLAGS (POSIX_SPAWN_RESETIDS                                       \
+                   | POSIX_SPAWN_SETPGROUP                                    \
+                   | POSIX_SPAWN_SETSIGDEF                                    \
+                   | POSIX_SPAWN_SETSIGMASK                                   \
+                   | POSIX_SPAWN_SETSCHEDPARAM                                \
+                   | POSIX_SPAWN_SETSCHEDULER                                 \
+                   | POSIX_SPAWN_USEVFORK)
+
+/* Store flags in the attribute structure.  */
+int
+posix_spawnattr_setflags (posix_spawnattr_t *attr, short int flags)
+{
+  /* Check no invalid bits are set.  */
+  if (flags & ~ALL_FLAGS)
+    return EINVAL;
+
+  /* Store the flag word.  */
+  attr->_flags = flags;
+
+  return 0;
+}
diff --git a/lib/spawnattr_setpgroup.c b/lib/spawnattr_setpgroup.c
new file mode 100644
index 00000000000..479457ad23e
--- /dev/null
+++ b/lib/spawnattr_setpgroup.c
@@ -0,0 +1,32 @@
+/* Copyright (C) 2000, 2009-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+
+#include <string.h>
+
+/* Store process group ID in the attribute structure.  */
+int
+posix_spawnattr_setpgroup (posix_spawnattr_t *attr, pid_t pgroup)
+{
+  /* Store the process group ID.  */
+  attr->_pgrp = pgroup;
+
+  return 0;
+}
diff --git a/lib/spawnattr_setsigmask.c b/lib/spawnattr_setsigmask.c
new file mode 100644
index 00000000000..9b6f9ece38e
--- /dev/null
+++ b/lib/spawnattr_setsigmask.c
@@ -0,0 +1,33 @@
+/* Copyright (C) 2000, 2009-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+
+#include <string.h>
+
+/* Set signal mask for the new process in ATTR to SIGMASK.  */
+int
+posix_spawnattr_setsigmask (posix_spawnattr_t *attr,
+                            const sigset_t *sigmask)
+{
+  /* Copy the sigset_t data to the user buffer.  */
+  memcpy (&attr->_ss, sigmask, sizeof (sigset_t));
+
+  return 0;
+}
diff --git a/lib/spawni.c b/lib/spawni.c
new file mode 100644
index 00000000000..182d13ff24c
--- /dev/null
+++ b/lib/spawni.c
@@ -0,0 +1,349 @@
+/* Guts of POSIX spawn interface.  Generic POSIX.1 version.
+   Copyright (C) 2000-2006, 2008-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <spawn.h>
+#include "spawn_int.h"
+
+#include <alloca.h>
+#include <errno.h>
+
+#include <fcntl.h>
+#ifndef O_LARGEFILE
+# define O_LARGEFILE 0
+#endif
+
+#if _LIBC || HAVE_PATHS_H
+# include <paths.h>
+#else
+# define _PATH_BSHELL BOURNE_SHELL
+#endif
+
+#include <signal.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#if _LIBC
+# include <not-cancel.h>
+#else
+# define close_not_cancel close
+# define open_not_cancel open
+#endif
+
+#if _LIBC
+# include <local-setxid.h>
+#else
+# if !HAVE_SETEUID
+#  define seteuid(id) setresuid (-1, id, -1)
+# endif
+# if !HAVE_SETEGID
+#  define setegid(id) setresgid (-1, id, -1)
+# endif
+# define local_seteuid(id) seteuid (id)
+# define local_setegid(id) setegid (id)
+#endif
+
+#if _LIBC
+# define alloca __alloca
+# define execve __execve
+# define dup2 __dup2
+# define fork __fork
+# define getgid __getgid
+# define getuid __getuid
+# define sched_setparam __sched_setparam
+# define sched_setscheduler __sched_setscheduler
+# define setpgid __setpgid
+# define sigaction __sigaction
+# define sigismember __sigismember
+# define sigprocmask __sigprocmask
+# define strchrnul __strchrnul
+# define vfork __vfork
+#endif
+
+
+/* The Unix standard contains a long explanation of the way to signal
+   an error after the fork() was successful.  Since no new wait status
+   was wanted there is no way to signal an error using one of the
+   available methods.  The committee chose to signal an error by a
+   normal program exit with the exit code 127.  */
+#define SPAWN_ERROR     127
+
+
+#if defined _WIN32 && ! defined __CYGWIN__
+
+/* Native Windows API.  */
+int
+__spawni (pid_t *pid, const char *file,
+          const posix_spawn_file_actions_t *file_actions,
+          const posix_spawnattr_t *attrp, const char *const argv[],
+          const char *const envp[], int use_path)
+{
+  /* Not yet implemented.  */
+  return ENOSYS;
+}
+
+#else
+
+
+/* Spawn a new process executing PATH with the attributes describes in *ATTRP.
+   Before running the process perform the actions described in FILE-ACTIONS. */
+int
+__spawni (pid_t *pid, const char *file,
+          const posix_spawn_file_actions_t *file_actions,
+          const posix_spawnattr_t *attrp, const char *const argv[],
+          const char *const envp[], int use_path)
+{
+  pid_t new_pid;
+  char *path, *p, *name;
+  size_t len;
+  size_t pathlen;
+
+  /* Do this once.  */
+  short int flags = attrp == NULL ? 0 : attrp->_flags;
+
+  /* Avoid gcc warning
+       "variable 'flags' might be clobbered by 'longjmp' or 'vfork'"  */
+  (void) &flags;
+
+  /* Generate the new process.  */
+#if HAVE_VFORK
+  if ((flags & POSIX_SPAWN_USEVFORK) != 0
+      /* If no major work is done, allow using vfork.  Note that we
+         might perform the path searching.  But this would be done by
+         a call to execvp(), too, and such a call must be OK according
+         to POSIX.  */
+      || ((flags & (POSIX_SPAWN_SETSIGMASK | POSIX_SPAWN_SETSIGDEF
+                    | POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER
+                    | POSIX_SPAWN_SETPGROUP | POSIX_SPAWN_RESETIDS)) == 0
+          && file_actions == NULL))
+    new_pid = vfork ();
+  else
+#endif
+    new_pid = fork ();
+
+  if (new_pid != 0)
+    {
+      if (new_pid < 0)
+        return errno;
+
+      /* The call was successful.  Store the PID if necessary.  */
+      if (pid != NULL)
+        *pid = new_pid;
+
+      return 0;
+    }
+
+  /* Set signal mask.  */
+  if ((flags & POSIX_SPAWN_SETSIGMASK) != 0
+      && sigprocmask (SIG_SETMASK, &attrp->_ss, NULL) != 0)
+    _exit (SPAWN_ERROR);
+
+  /* Set signal default action.  */
+  if ((flags & POSIX_SPAWN_SETSIGDEF) != 0)
+    {
+      /* We have to iterate over all signals.  This could possibly be
+         done better but it requires system specific solutions since
+         the sigset_t data type can be very different on different
+         architectures.  */
+      int sig;
+      struct sigaction sa;
+
+      memset (&sa, '\0', sizeof (sa));
+      sa.sa_handler = SIG_DFL;
+
+      for (sig = 1; sig <= NSIG; ++sig)
+        if (sigismember (&attrp->_sd, sig) != 0
+            && sigaction (sig, &sa, NULL) != 0)
+          _exit (SPAWN_ERROR);
+
+    }
+
+#if (_LIBC ? defined _POSIX_PRIORITY_SCHEDULING : HAVE_SCHED_SETPARAM && HAVE_SCHED_SETSCHEDULER)
+  /* Set the scheduling algorithm and parameters.  */
+  if ((flags & (POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER))
+      == POSIX_SPAWN_SETSCHEDPARAM)
+    {
+      if (sched_setparam (0, &attrp->_sp) == -1)
+        _exit (SPAWN_ERROR);
+    }
+  else if ((flags & POSIX_SPAWN_SETSCHEDULER) != 0)
+    {
+      if (sched_setscheduler (0, attrp->_policy,
+                              (flags & POSIX_SPAWN_SETSCHEDPARAM) != 0
+                              ? &attrp->_sp : NULL) == -1)
+        _exit (SPAWN_ERROR);
+    }
+#endif
+
+  /* Set the process group ID.  */
+  if ((flags & POSIX_SPAWN_SETPGROUP) != 0
+      && setpgid (0, attrp->_pgrp) != 0)
+    _exit (SPAWN_ERROR);
+
+  /* Set the effective user and group IDs.  */
+  if ((flags & POSIX_SPAWN_RESETIDS) != 0
+      && (local_seteuid (getuid ()) != 0
+          || local_setegid (getgid ()) != 0))
+    _exit (SPAWN_ERROR);
+
+  /* Execute the file actions.  */
+  if (file_actions != NULL)
+    {
+      int cnt;
+
+      for (cnt = 0; cnt < file_actions->_used; ++cnt)
+        {
+          struct __spawn_action *action = &file_actions->_actions[cnt];
+
+          switch (action->tag)
+            {
+            case spawn_do_close:
+              if (close_not_cancel (action->action.close_action.fd) != 0)
+                /* Signal the error.  */
+                _exit (SPAWN_ERROR);
+              break;
+
+            case spawn_do_open:
+              {
+                int new_fd = open_not_cancel (action->action.open_action.path,
+                                              action->action.open_action.oflag
+                                              | O_LARGEFILE,
+                                              action->action.open_action.mode);
+
+                if (new_fd == -1)
+                  /* The 'open' call failed.  */
+                  _exit (SPAWN_ERROR);
+
+                /* Make sure the desired file descriptor is used.  */
+                if (new_fd != action->action.open_action.fd)
+                  {
+                    if (dup2 (new_fd, action->action.open_action.fd)
+                        != action->action.open_action.fd)
+                      /* The 'dup2' call failed.  */
+                      _exit (SPAWN_ERROR);
+
+                    if (close_not_cancel (new_fd) != 0)
+                      /* The 'close' call failed.  */
+                      _exit (SPAWN_ERROR);
+                  }
+              }
+              break;
+
+            case spawn_do_dup2:
+              if (dup2 (action->action.dup2_action.fd,
+                        action->action.dup2_action.newfd)
+                  != action->action.dup2_action.newfd)
+                /* The 'dup2' call failed.  */
+                _exit (SPAWN_ERROR);
+              break;
+
+            case spawn_do_chdir:
+              if (chdir (action->action.chdir_action.path) < 0)
+                /* The 'chdir' call failed.  */
+                _exit (SPAWN_ERROR);
+              break;
+
+            case spawn_do_fchdir:
+              if (fchdir (action->action.fchdir_action.fd) < 0)
+                /* The 'fchdir' call failed.  */
+                _exit (SPAWN_ERROR);
+              break;
+            }
+        }
+    }
+
+  if (! use_path || strchr (file, '/') != NULL)
+    {
+      /* The FILE parameter is actually a path.  */
+      execve (file, (char * const *) argv, (char * const *) envp);
+
+      /* Oh, oh.  'execve' returns.  This is bad.  */
+      _exit (SPAWN_ERROR);
+    }
+
+  /* We have to search for FILE on the path.  */
+  path = getenv ("PATH");
+  if (path == NULL)
+    {
+#if HAVE_CONFSTR
+      /* There is no 'PATH' in the environment.
+         The default search path is the current directory
+         followed by the path 'confstr' returns for '_CS_PATH'.  */
+      len = confstr (_CS_PATH, (char *) NULL, 0);
+      path = (char *) alloca (1 + len);
+      path[0] = ':';
+      (void) confstr (_CS_PATH, path + 1, len);
+#else
+      /* Pretend that the PATH contains only the current directory.  */
+      path = "";
+#endif
+    }
+
+  len = strlen (file) + 1;
+  pathlen = strlen (path);
+  name = alloca (pathlen + len + 1);
+  /* Copy the file name at the top.  */
+  name = (char *) memcpy (name + pathlen + 1, file, len);
+  /* And add the slash.  */
+  *--name = '/';
+
+  p = path;
+  do
+    {
+      char *startp;
+
+      path = p;
+      p = strchrnul (path, ':');
+
+      if (p == path)
+        /* Two adjacent colons, or a colon at the beginning or the end
+           of 'PATH' means to search the current directory.  */
+        startp = name + 1;
+      else
+        startp = (char *) memcpy (name - (p - path), path, p - path);
+
+      /* Try to execute this name.  If it works, execv will not return.  */
+      execve (startp, (char * const *) argv, (char * const *) envp);
+
+      switch (errno)
+        {
+        case EACCES:
+        case ENOENT:
+        case ESTALE:
+        case ENOTDIR:
+          /* Those errors indicate the file is missing or not executable
+             by us, in which case we want to just try the next path
+             directory.  */
+          break;
+
+        default:
+          /* Some other error means we found an executable file, but
+             something went wrong executing it; return the error to our
+             caller.  */
+          _exit (SPAWN_ERROR);
+        }
+    }
+  while (*p++ != '\0');
+
+  /* Return with an error.  */
+  _exit (SPAWN_ERROR);
+}
+
+#endif
diff --git a/lib/strchrnul.c b/lib/strchrnul.c
new file mode 100644
index 00000000000..858d66fab18
--- /dev/null
+++ b/lib/strchrnul.c
@@ -0,0 +1,142 @@
+/* Searching in a string.
+   Copyright (C) 2003, 2007-2020 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <string.h>
+
+/* Find the first occurrence of C in S or the final NUL byte.  */
+char *
+strchrnul (const char *s, int c_in)
+{
+  /* On 32-bit hardware, choosing longword to be a 32-bit unsigned
+     long instead of a 64-bit uintmax_t tends to give better
+     performance.  On 64-bit hardware, unsigned long is generally 64
+     bits already.  Change this typedef to experiment with
+     performance.  */
+  typedef unsigned long int longword;
+
+  const unsigned char *char_ptr;
+  const longword *longword_ptr;
+  longword repeated_one;
+  longword repeated_c;
+  unsigned char c;
+
+  c = (unsigned char) c_in;
+  if (!c)
+    return rawmemchr (s, 0);
+
+  /* Handle the first few bytes by reading one byte at a time.
+     Do this until CHAR_PTR is aligned on a longword boundary.  */
+  for (char_ptr = (const unsigned char *) s;
+       (size_t) char_ptr % sizeof (longword) != 0;
+       ++char_ptr)
+    if (!*char_ptr || *char_ptr == c)
+      return (char *) char_ptr;
+
+  longword_ptr = (const longword *) char_ptr;
+
+  /* All these elucidatory comments refer to 4-byte longwords,
+     but the theory applies equally well to any size longwords.  */
+
+  /* Compute auxiliary longword values:
+     repeated_one is a value which has a 1 in every byte.
+     repeated_c has c in every byte.  */
+  repeated_one = 0x01010101;
+  repeated_c = c | (c << 8);
+  repeated_c |= repeated_c << 16;
+  if (0xffffffffU < (longword) -1)
+    {
+      repeated_one |= repeated_one << 31 << 1;
+      repeated_c |= repeated_c << 31 << 1;
+      if (8 < sizeof (longword))
+        {
+          size_t i;
+
+          for (i = 64; i < sizeof (longword) * 8; i *= 2)
+            {
+              repeated_one |= repeated_one << i;
+              repeated_c |= repeated_c << i;
+            }
+        }
+    }
+
+  /* Instead of the traditional loop which tests each byte, we will
+     test a longword at a time.  The tricky part is testing if *any of
+     the four* bytes in the longword in question are equal to NUL or
+     c.  We first use an xor with repeated_c.  This reduces the task
+     to testing whether *any of the four* bytes in longword1 or
+     longword2 is zero.
+
+     Let's consider longword1.  We compute tmp =
+       ((longword1 - repeated_one) & ~longword1) & (repeated_one << 7).
+     That is, we perform the following operations:
+       1. Subtract repeated_one.
+       2. & ~longword1.
+       3. & a mask consisting of 0x80 in every byte.
+     Consider what happens in each byte:
+       - If a byte of longword1 is zero, step 1 and 2 transform it into 0xff,
+         and step 3 transforms it into 0x80.  A carry can also be propagated
+         to more significant bytes.
+       - If a byte of longword1 is nonzero, let its lowest 1 bit be at
+         position k (0 <= k <= 7); so the lowest k bits are 0.  After step 1,
+         the byte ends in a single bit of value 0 and k bits of value 1.
+         After step 2, the result is just k bits of value 1: 2^k - 1.  After
+         step 3, the result is 0.  And no carry is produced.
+     So, if longword1 has only non-zero bytes, tmp is zero.
+     Whereas if longword1 has a zero byte, call j the position of the least
+     significant zero byte.  Then the result has a zero at positions 0, ...,
+     j-1 and a 0x80 at position j.  We cannot predict the result at the more
+     significant bytes (positions j+1..3), but it does not matter since we
+     already have a non-zero bit at position 8*j+7.
+
+     The test whether any byte in longword1 or longword2 is zero is equivalent
+     to testing whether tmp1 is nonzero or tmp2 is nonzero.  We can combine
+     this into a single test, whether (tmp1 | tmp2) is nonzero.
+
+     This test can read more than one byte beyond the end of a string,
+     depending on where the terminating NUL is encountered.  However,
+     this is considered safe since the initialization phase ensured
+     that the read will be aligned, therefore, the read will not cross
+     page boundaries and will not cause a fault.  */
+
+  while (1)
+    {
+      longword longword1 = *longword_ptr ^ repeated_c;
+      longword longword2 = *longword_ptr;
+
+      if (((((longword1 - repeated_one) & ~longword1)
+            | ((longword2 - repeated_one) & ~longword2))
+           & (repeated_one << 7)) != 0)
+        break;
+      longword_ptr++;
+    }
+
+  char_ptr = (const unsigned char *) longword_ptr;
+
+  /* At this point, we know that one of the sizeof (longword) bytes
+     starting at char_ptr is == 0 or == c.  On little-endian machines,
+     we could determine the first such byte without any further memory
+     accesses, just by looking at the tmp result from the last loop
+     iteration.  But this does not work on big-endian machines.
+     Choose code that works in both cases.  */
+
+  char_ptr = (unsigned char *) longword_ptr;
+  while (*char_ptr && (*char_ptr != c))
+    char_ptr++;
+  return (char *) char_ptr;
+}
diff --git a/lib/strchrnul.valgrind b/lib/strchrnul.valgrind
new file mode 100644
index 00000000000..a85608a7c76
--- /dev/null
+++ b/lib/strchrnul.valgrind
@@ -0,0 +1,28 @@
+# Suppress a valgrind message about use of uninitialized memory in strchrnul().
+
+# Copyright (C) 2008-2020 Free Software Foundation, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+# This use is OK because it provides only a speedup.
+{
+    strchrnul-value4
+    Memcheck:Value4
+    fun:strchrnul
+}
+{
+    strchrnul-value8
+    Memcheck:Value8
+    fun:strchrnul
+}
diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index 0971636c33d..e2a44efe621 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -139,6 +139,18 @@ AC_DEFUN([gl_EARLY],
   # Code from module openat-h:
   # Code from module pathmax:
   # Code from module pipe2:
+  # Code from module posix_spawn:
+  # Code from module posix_spawn-internal:
+  # Code from module posix_spawn_file_actions_addchdir:
+  # Code from module posix_spawn_file_actions_adddup2:
+  # Code from module posix_spawn_file_actions_destroy:
+  # Code from module posix_spawn_file_actions_init:
+  # Code from module posix_spawnattr_destroy:
+  # Code from module posix_spawnattr_init:
+  # Code from module posix_spawnattr_setflags:
+  # Code from module posix_spawnattr_setpgroup:
+  # Code from module posix_spawnattr_setsigdefault:
+  # Code from module posix_spawnattr_setsigmask:
   # Code from module pselect:
   # Code from module pthread_sigmask:
   # Code from module qcopy-acl:
@@ -147,7 +159,9 @@ AC_DEFUN([gl_EARLY],
   # Code from module readlinkat:
   # Code from module regex:
   # Code from module root-uid:
+  # Code from module sched:
   # Code from module scratch_buffer:
+  # Code from module sh-filename:
   # Code from module sig2str:
   # Code from module sigdescr_np:
   # Code from module signal-h:
@@ -156,6 +170,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module snippet/c++defs:
   # Code from module snippet/warn-on-use:
   # Code from module socklen:
+  # Code from module spawn:
   # Code from module ssize_t:
   # Code from module stat-time:
   # Code from module std-gnu11:
@@ -165,6 +180,7 @@ AC_DEFUN([gl_EARLY],
   # Code from module stdio:
   # Code from module stdlib:
   # Code from module stpcpy:
+  # Code from module strchrnul:
   # Code from module string:
   # Code from module strnlen:
   # Code from module strtoimax:
@@ -403,6 +419,61 @@ AC_DEFUN([gl_INIT],
   gl_PATHMAX
   gl_FUNC_PIPE2
   gl_UNISTD_MODULE_INDICATOR([pipe2])
+  gl_POSIX_SPAWN
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+    AC_LIBOBJ([spawn])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawn])
+  gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1 || test $HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR = 0 || test $REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR = 1; then
+    AC_LIBOBJ([spawn_faction_addchdir])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawn_file_actions_addchdir])
+  gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1 || test $REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2 = 1; then
+    AC_LIBOBJ([spawn_faction_adddup2])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawn_file_actions_adddup2])
+  gl_POSIX_SPAWN
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+    AC_LIBOBJ([spawn_faction_destroy])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawn_file_actions_destroy])
+  gl_POSIX_SPAWN
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+    AC_LIBOBJ([spawn_faction_init])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawn_file_actions_init])
+  gl_POSIX_SPAWN
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+    AC_LIBOBJ([spawnattr_destroy])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawnattr_destroy])
+  gl_POSIX_SPAWN
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+    AC_LIBOBJ([spawnattr_init])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawnattr_init])
+  gl_POSIX_SPAWN
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+    AC_LIBOBJ([spawnattr_setflags])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawnattr_setflags])
+  gl_POSIX_SPAWN
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+    AC_LIBOBJ([spawnattr_setpgroup])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawnattr_setpgroup])
+  gl_POSIX_SPAWN
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+    AC_LIBOBJ([spawnattr_setdefault])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawnattr_setsigdefault])
+  gl_POSIX_SPAWN
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+    AC_LIBOBJ([spawnattr_setsigmask])
+  fi
+  gl_SPAWN_MODULE_INDICATOR([posix_spawnattr_setsigmask])
   gl_FUNC_PSELECT
   if test $HAVE_PSELECT = 0 || test $REPLACE_PSELECT = 1; then
     AC_LIBOBJ([pselect])
@@ -430,6 +501,7 @@ AC_DEFUN([gl_INIT],
     AC_LIBOBJ([regex])
     gl_PREREQ_REGEX
   fi
+  gl_SCHED_H
   gl_FUNC_SIG2STR
   if test $ac_cv_func_sig2str = no; then
     AC_LIBOBJ([sig2str])
@@ -442,6 +514,7 @@ AC_DEFUN([gl_INIT],
   gl_STRING_MODULE_INDICATOR([sigdescr_np])
   gl_SIGNAL_H
   gl_TYPE_SOCKLEN_T
+  gl_SPAWN_H
   gt_TYPE_SSIZE_T
   gl_STAT_TIME
   gl_STAT_BIRTHTIME
@@ -528,9 +601,12 @@ AC_DEFUN([gl_INIT],
   gl_gnulib_enabled_5264294aa0a5557541b53c8c741f7f31=false
   gl_gnulib_enabled_open=false
   gl_gnulib_enabled_03e0aaad4cb89ca757653bd367a6ccb7=false
+  gl_gnulib_enabled_332607f759618fb73dfc3076748afea7=false
   gl_gnulib_enabled_rawmemchr=false
   gl_gnulib_enabled_6099e9737f757db36c47fa9d9f02e88c=false
   gl_gnulib_enabled_scratch_buffer=false
+  gl_gnulib_enabled_cdeb0f2aaf9d280baa6526bfa1b07f70=false
+  gl_gnulib_enabled_strchrnul=false
   gl_gnulib_enabled_strtoll=false
   gl_gnulib_enabled_utimens=false
   gl_gnulib_enabled_682e609604ccaac6be382e4ee3a4eaec=false
@@ -685,6 +761,20 @@ AC_DEFUN([gl_INIT],
       gl_gnulib_enabled_03e0aaad4cb89ca757653bd367a6ccb7=true
     fi
   }
+  func_gl_gnulib_m4code_332607f759618fb73dfc3076748afea7 ()
+  {
+    if ! $gl_gnulib_enabled_332607f759618fb73dfc3076748afea7; then
+      gl_POSIX_SPAWN
+      if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+        AC_LIBOBJ([spawni])
+        gl_PREREQ_POSIX_SPAWN_INTERNAL
+      fi
+      gl_gnulib_enabled_332607f759618fb73dfc3076748afea7=true
+      func_gl_gnulib_m4code_open
+      func_gl_gnulib_m4code_cdeb0f2aaf9d280baa6526bfa1b07f70
+      func_gl_gnulib_m4code_strchrnul
+    fi
+  }
   func_gl_gnulib_m4code_rawmemchr ()
   {
     if ! $gl_gnulib_enabled_rawmemchr; then
@@ -709,6 +799,28 @@ AC_DEFUN([gl_INIT],
       gl_gnulib_enabled_scratch_buffer=true
     fi
   }
+  func_gl_gnulib_m4code_cdeb0f2aaf9d280baa6526bfa1b07f70 ()
+  {
+    if ! $gl_gnulib_enabled_cdeb0f2aaf9d280baa6526bfa1b07f70; then
+      gl_SH_FILENAME
+      gl_gnulib_enabled_cdeb0f2aaf9d280baa6526bfa1b07f70=true
+    fi
+  }
+  func_gl_gnulib_m4code_strchrnul ()
+  {
+    if ! $gl_gnulib_enabled_strchrnul; then
+      gl_FUNC_STRCHRNUL
+      if test $HAVE_STRCHRNUL = 0 || test $REPLACE_STRCHRNUL = 1; then
+        AC_LIBOBJ([strchrnul])
+        gl_PREREQ_STRCHRNUL
+      fi
+      gl_STRING_MODULE_INDICATOR([strchrnul])
+      gl_gnulib_enabled_strchrnul=true
+      if test $HAVE_STRCHRNUL = 0 || test $REPLACE_STRCHRNUL = 1; then
+        func_gl_gnulib_m4code_rawmemchr
+      fi
+    fi
+  }
   func_gl_gnulib_m4code_strtoll ()
   {
     if ! $gl_gnulib_enabled_strtoll; then
@@ -791,6 +903,12 @@ AC_DEFUN([gl_INIT],
   if case $host_os in mingw*) false;; *) test $HAVE_GETRANDOM = 0 || test $REPLACE_GETRANDOM = 1;; esac; then
     func_gl_gnulib_m4code_open
   fi
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1; then
+    func_gl_gnulib_m4code_332607f759618fb73dfc3076748afea7
+  fi
+  if test $HAVE_POSIX_SPAWN = 0 || test $REPLACE_POSIX_SPAWN = 1 || test $REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2 = 1; then
+    func_gl_gnulib_m4code_getdtablesize
+  fi
   if test $HAVE_READLINKAT = 0 || test $REPLACE_READLINKAT = 1; then
     func_gl_gnulib_m4code_260941c0e5dc67ec9e87d1fb321c300b
   fi
@@ -830,9 +948,12 @@ AC_DEFUN([gl_INIT],
   AM_CONDITIONAL([gl_GNULIB_ENABLED_5264294aa0a5557541b53c8c741f7f31], [$gl_gnulib_enabled_5264294aa0a5557541b53c8c741f7f31])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_open], [$gl_gnulib_enabled_open])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_03e0aaad4cb89ca757653bd367a6ccb7], [$gl_gnulib_enabled_03e0aaad4cb89ca757653bd367a6ccb7])
+  AM_CONDITIONAL([gl_GNULIB_ENABLED_332607f759618fb73dfc3076748afea7], [$gl_gnulib_enabled_332607f759618fb73dfc3076748afea7])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_rawmemchr], [$gl_gnulib_enabled_rawmemchr])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_6099e9737f757db36c47fa9d9f02e88c], [$gl_gnulib_enabled_6099e9737f757db36c47fa9d9f02e88c])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_scratch_buffer], [$gl_gnulib_enabled_scratch_buffer])
+  AM_CONDITIONAL([gl_GNULIB_ENABLED_cdeb0f2aaf9d280baa6526bfa1b07f70], [$gl_gnulib_enabled_cdeb0f2aaf9d280baa6526bfa1b07f70])
+  AM_CONDITIONAL([gl_GNULIB_ENABLED_strchrnul], [$gl_gnulib_enabled_strchrnul])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_strtoll], [$gl_gnulib_enabled_strtoll])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_utimens], [$gl_gnulib_enabled_utimens])
   AM_CONDITIONAL([gl_GNULIB_ENABLED_682e609604ccaac6be382e4ee3a4eaec], [$gl_gnulib_enabled_682e609604ccaac6be382e4ee3a4eaec])
@@ -1113,6 +1234,7 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/regex_internal.h
   lib/regexec.c
   lib/root-uid.h
+  lib/sched.in.h
   lib/scratch_buffer.h
   lib/set-permissions.c
   lib/sha1.c
@@ -1125,6 +1247,20 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/sig2str.h
   lib/sigdescr_np.c
   lib/signal.in.h
+  lib/spawn.c
+  lib/spawn.in.h
+  lib/spawn_faction_addchdir.c
+  lib/spawn_faction_adddup2.c
+  lib/spawn_faction_destroy.c
+  lib/spawn_faction_init.c
+  lib/spawn_int.h
+  lib/spawnattr_destroy.c
+  lib/spawnattr_init.c
+  lib/spawnattr_setdefault.c
+  lib/spawnattr_setflags.c
+  lib/spawnattr_setpgroup.c
+  lib/spawnattr_setsigmask.c
+  lib/spawni.c
   lib/stat-time.c
   lib/stat-time.h
   lib/stdalign.in.h
@@ -1135,6 +1271,8 @@ AC_DEFUN([gl_FILE_LIST], [
   lib/stdlib.in.h
   lib/stpcpy.c
   lib/str-two-way.h
+  lib/strchrnul.c
+  lib/strchrnul.valgrind
   lib/strftime.h
   lib/string.in.h
   lib/strnlen.c
@@ -1248,12 +1386,16 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/pathmax.m4
   m4/pid_t.m4
   m4/pipe2.m4
+  m4/posix_spawn.m4
+  m4/posix_spawn_faction_addchdir.m4
   m4/pselect.m4
   m4/pthread_sigmask.m4
   m4/rawmemchr.m4
   m4/readlink.m4
   m4/readlinkat.m4
   m4/regex.m4
+  m4/sched_h.m4
+  m4/sh-filename.m4
   m4/sha1.m4
   m4/sha256.m4
   m4/sha512.m4
@@ -1261,6 +1403,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/sigdescr_np.m4
   m4/signal_h.m4
   m4/socklen.m4
+  m4/spawn_h.m4
   m4/ssize_t.m4
   m4/stat-time.m4
   m4/std-gnu11.m4
@@ -1270,6 +1413,7 @@ AC_DEFUN([gl_FILE_LIST], [
   m4/stdio_h.m4
   m4/stdlib_h.m4
   m4/stpcpy.m4
+  m4/strchrnul.m4
   m4/string_h.m4
   m4/strnlen.m4
   m4/strtoimax.m4
diff --git a/m4/posix_spawn.m4 b/m4/posix_spawn.m4
new file mode 100644
index 00000000000..59e56fcb5f2
--- /dev/null
+++ b/m4/posix_spawn.m4
@@ -0,0 +1,678 @@
+# posix_spawn.m4 serial 19
+dnl Copyright (C) 2008-2020 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Tests whether the entire posix_spawn facility is available.
+AC_DEFUN([gl_POSIX_SPAWN],
+[
+  AC_REQUIRE([gl_POSIX_SPAWN_BODY])
+])
+
+AC_DEFUN([gl_POSIX_SPAWN_BODY],
+[
+  AC_REQUIRE([gl_SPAWN_H_DEFAULTS])
+  AC_REQUIRE([gl_HAVE_POSIX_SPAWN])
+  dnl Assume that when the main function exists, all the others,
+  dnl except posix_spawnattr_{get,set}sched*, are available as well.
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawnp])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawn_file_actions_init])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawn_file_actions_addclose])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawn_file_actions_adddup2])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawn_file_actions_addopen])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawn_file_actions_destroy])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_init])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_getflags])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_setflags])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_getpgroup])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_setpgroup])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_getsigdefault])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_setsigdefault])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_getsigmask])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_setsigmask])
+  dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_destroy])
+  if test $ac_cv_func_posix_spawn = yes; then
+    m4_ifdef([gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR],
+      [dnl Module 'posix_spawn_file_actions_addchdir' is present.
+       AC_CHECK_FUNCS_ONCE([posix_spawn_file_actions_addchdir_np])
+       if test $ac_cv_func_posix_spawn_file_actions_addchdir_np = no; then
+         dnl In order to implement the posix_spawn_file_actions_addchdir
+         dnl function, we need to replace the entire posix_spawn facility.
+         REPLACE_POSIX_SPAWN=1
+       fi
+      ])
+    m4_ifdef([gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR],
+      [dnl Module 'posix_spawn_file_actions_addfchdir' is present.
+       AC_CHECK_FUNCS_ONCE([posix_spawn_file_actions_addfchdir_np])
+       if test $ac_cv_func_posix_spawn_file_actions_addfchdir_np = no; then
+         dnl In order to implement the posix_spawn_file_actions_addfchdir
+         dnl function, we need to replace the entire posix_spawn facility.
+         REPLACE_POSIX_SPAWN=1
+       fi
+      ])
+    if test $REPLACE_POSIX_SPAWN = 0; then
+      gl_POSIX_SPAWN_WORKS
+      case "$gl_cv_func_posix_spawn_works" in
+        *yes) ;;
+        *) REPLACE_POSIX_SPAWN=1 ;;
+      esac
+    fi
+    if test $REPLACE_POSIX_SPAWN = 0; then
+      gl_POSIX_SPAWN_SECURE
+      case "$gl_cv_func_posix_spawn_secure_exec" in
+        *yes) ;;
+        *) REPLACE_POSIX_SPAWN=1 ;;
+      esac
+      case "$gl_cv_func_posix_spawnp_secure_exec" in
+        *yes) ;;
+        *) REPLACE_POSIX_SPAWN=1 ;;
+      esac
+    fi
+    if test $REPLACE_POSIX_SPAWN = 0; then
+      dnl Assume that these functions are available if POSIX_SPAWN_SETSCHEDULER
+      dnl evaluates to nonzero.
+      dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_getschedpolicy])
+      dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_setschedpolicy])
+      AC_CACHE_CHECK([whether posix_spawnattr_setschedpolicy is supported],
+        [gl_cv_func_spawnattr_setschedpolicy],
+        [AC_EGREP_CPP([POSIX scheduling supported], [
+#include <spawn.h>
+#if POSIX_SPAWN_SETSCHEDULER
+ POSIX scheduling supported
+#endif
+],
+           [gl_cv_func_spawnattr_setschedpolicy=yes],
+           [gl_cv_func_spawnattr_setschedpolicy=no])
+        ])
+      dnl Assume that these functions are available if POSIX_SPAWN_SETSCHEDPARAM
+      dnl evaluates to nonzero.
+      dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_getschedparam])
+      dnl AC_CHECK_FUNCS_ONCE([posix_spawnattr_setschedparam])
+      AC_CACHE_CHECK([whether posix_spawnattr_setschedparam is supported],
+        [gl_cv_func_spawnattr_setschedparam],
+        [AC_EGREP_CPP([POSIX scheduling supported], [
+#include <spawn.h>
+#if POSIX_SPAWN_SETSCHEDPARAM
+ POSIX scheduling supported
+#endif
+],
+           [gl_cv_func_spawnattr_setschedparam=yes],
+           [gl_cv_func_spawnattr_setschedparam=no])
+        ])
+    fi
+  fi
+  if test $ac_cv_func_posix_spawn != yes || test $REPLACE_POSIX_SPAWN = 1; then
+    AC_DEFINE([REPLACE_POSIX_SPAWN], [1],
+      [Define if gnulib uses its own posix_spawn and posix_spawnp functions.])
+  fi
+])
+
+dnl Test whether posix_spawn actually works.
+dnl posix_spawn on AIX 5.3..6.1 has two bugs:
+dnl 1) When it fails to execute the program, the child process exits with
+dnl    exit() rather than _exit(), which causes the stdio buffers to be
+dnl    flushed. Reported by Rainer Tammer.
+dnl 2) The posix_spawn_file_actions_addopen function does not support file
+dnl    names that contain a '*'.
+dnl posix_spawn on AIX 5.3..6.1 has also a third bug: It does not work
+dnl when POSIX threads are used. But we don't test against this bug here.
+AC_DEFUN([gl_POSIX_SPAWN_WORKS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  AC_CACHE_CHECK([whether posix_spawn works], [gl_cv_func_posix_spawn_works],
+    [if test $cross_compiling = no; then
+       AC_LINK_IFELSE([AC_LANG_SOURCE([[
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <spawn.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+]GL_MDA_DEFINES[
+
+extern char **environ;
+
+#ifndef STDIN_FILENO
+# define STDIN_FILENO 0
+#endif
+#ifndef STDOUT_FILENO
+# define STDOUT_FILENO 1
+#endif
+#ifndef STDERR_FILENO
+# define STDERR_FILENO 2
+#endif
+
+#ifndef WTERMSIG
+# define WTERMSIG(x) ((x) & 0x7f)
+#endif
+#ifndef WIFEXITED
+# define WIFEXITED(x) (WTERMSIG (x) == 0)
+#endif
+#ifndef WEXITSTATUS
+# define WEXITSTATUS(x) (((x) >> 8) & 0xff)
+#endif
+
+#define CHILD_PROGRAM_FILENAME "/non/exist/ent"
+
+static int
+fd_safer (int fd)
+{
+  if (0 <= fd && fd <= 2)
+    {
+      int f = fd_safer (dup (fd));
+      int e = errno;
+      close (fd);
+      errno = e;
+      fd = f;
+    }
+
+  return fd;
+}
+
+int
+main ()
+{
+  char *argv[2] = { CHILD_PROGRAM_FILENAME, NULL };
+  int ofd[2];
+  sigset_t blocked_signals;
+  sigset_t fatal_signal_set;
+  posix_spawn_file_actions_t actions;
+  bool actions_allocated;
+  posix_spawnattr_t attrs;
+  bool attrs_allocated;
+  int err;
+  pid_t child;
+  int status;
+  int exitstatus;
+
+  setvbuf (stdout, NULL, _IOFBF, 0);
+  puts ("This should be seen only once.");
+  if (pipe (ofd) < 0 || (ofd[1] = fd_safer (ofd[1])) < 0)
+    {
+      perror ("cannot create pipe");
+      exit (1);
+    }
+  sigprocmask (SIG_SETMASK, NULL, &blocked_signals);
+  sigemptyset (&fatal_signal_set);
+  sigaddset (&fatal_signal_set, SIGINT);
+  sigaddset (&fatal_signal_set, SIGTERM);
+  sigaddset (&fatal_signal_set, SIGHUP);
+  sigaddset (&fatal_signal_set, SIGPIPE);
+  sigprocmask (SIG_BLOCK, &fatal_signal_set, NULL);
+  actions_allocated = false;
+  attrs_allocated = false;
+  if ((err = posix_spawn_file_actions_init (&actions)) != 0
+      || (actions_allocated = true,
+          (err = posix_spawn_file_actions_adddup2 (&actions, ofd[0], STDIN_FILENO)) != 0
+          || (err = posix_spawn_file_actions_addclose (&actions, ofd[0])) != 0
+          || (err = posix_spawn_file_actions_addclose (&actions, ofd[1])) != 0
+          || (err = posix_spawnattr_init (&attrs)) != 0
+          || (attrs_allocated = true,
+              (err = posix_spawnattr_setsigmask (&attrs, &blocked_signals)) != 0
+              || (err = posix_spawnattr_setflags (&attrs, POSIX_SPAWN_SETSIGMASK)) != 0)
+          || (err = posix_spawnp (&child, CHILD_PROGRAM_FILENAME, &actions, &attrs, argv, environ)) != 0))
+    {
+      if (actions_allocated)
+        posix_spawn_file_actions_destroy (&actions);
+      if (attrs_allocated)
+        posix_spawnattr_destroy (&attrs);
+      sigprocmask (SIG_UNBLOCK, &fatal_signal_set, NULL);
+      if (err == ENOENT)
+        return 0;
+      else
+        {
+          errno = err;
+          perror ("subprocess failed");
+          exit (1);
+        }
+    }
+  posix_spawn_file_actions_destroy (&actions);
+  posix_spawnattr_destroy (&attrs);
+  sigprocmask (SIG_UNBLOCK, &fatal_signal_set, NULL);
+  close (ofd[0]);
+  close (ofd[1]);
+  status = 0;
+  while (waitpid (child, &status, 0) != child)
+    ;
+  if (!WIFEXITED (status))
+    {
+      fprintf (stderr, "subprocess terminated with unexpected wait status %d\n", status);
+      exit (1);
+    }
+  exitstatus = WEXITSTATUS (status);
+  if (exitstatus != 127)
+    {
+      fprintf (stderr, "subprocess terminated with unexpected exit status %d\n", exitstatus);
+      exit (1);
+    }
+  return 0;
+}
+]])],
+         [if test -s conftest$ac_exeext \
+             && ./conftest$ac_exeext > conftest.out \
+             && echo 'This should be seen only once.' > conftest.ok \
+             && cmp conftest.out conftest.ok >/dev/null 2>&1; then
+            gl_cv_func_posix_spawn_works=yes
+          else
+            gl_cv_func_posix_spawn_works=no
+          fi],
+         [gl_cv_func_posix_spawn_works=no])
+       if test $gl_cv_func_posix_spawn_works = yes; then
+         AC_RUN_IFELSE([AC_LANG_SOURCE([[
+/* Test whether posix_spawn_file_actions_addopen supports filename arguments
+   that contain special characters such as '*'.  */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <spawn.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+]GL_MDA_DEFINES[
+
+extern char **environ;
+
+#ifndef STDIN_FILENO
+# define STDIN_FILENO 0
+#endif
+#ifndef STDOUT_FILENO
+# define STDOUT_FILENO 1
+#endif
+#ifndef STDERR_FILENO
+# define STDERR_FILENO 2
+#endif
+
+#ifndef WTERMSIG
+# define WTERMSIG(x) ((x) & 0x7f)
+#endif
+#ifndef WIFEXITED
+# define WIFEXITED(x) (WTERMSIG (x) == 0)
+#endif
+#ifndef WEXITSTATUS
+# define WEXITSTATUS(x) (((x) >> 8) & 0xff)
+#endif
+
+#define CHILD_PROGRAM_FILENAME "conftest"
+#define DATA_FILENAME "conftest%=*#?"
+
+static int
+parent_main (void)
+{
+  FILE *fp;
+  char *argv[3] = { CHILD_PROGRAM_FILENAME, "-child", NULL };
+  posix_spawn_file_actions_t actions;
+  bool actions_allocated;
+  int err;
+  pid_t child;
+  int status;
+  int exitstatus;
+
+  /* Create a data file with specific contents.  */
+  fp = fopen (DATA_FILENAME, "wb");
+  if (fp == NULL)
+    {
+      perror ("cannot create data file");
+      return 1;
+    }
+  fwrite ("Halle Potta", 1, 11, fp);
+  if (fflush (fp) || fclose (fp))
+    {
+      perror ("cannot prepare data file");
+      return 2;
+    }
+
+  /* Avoid reading from our stdin, as it could block.  */
+  freopen ("/dev/null", "rb", stdin);
+
+  /* Test whether posix_spawn_file_actions_addopen with this file name
+     actually works, but spawning a child that reads from this file.  */
+  actions_allocated = false;
+  if ((err = posix_spawn_file_actions_init (&actions)) != 0
+      || (actions_allocated = true,
+          (err = posix_spawn_file_actions_addopen (&actions, STDIN_FILENO, DATA_FILENAME, O_RDONLY, 0600)) != 0
+          || (err = posix_spawn (&child, CHILD_PROGRAM_FILENAME, &actions, NULL, argv, environ)) != 0))
+    {
+      if (actions_allocated)
+        posix_spawn_file_actions_destroy (&actions);
+      errno = err;
+      perror ("subprocess failed");
+      return 3;
+    }
+  posix_spawn_file_actions_destroy (&actions);
+  status = 0;
+  while (waitpid (child, &status, 0) != child)
+    ;
+  if (!WIFEXITED (status))
+    {
+      fprintf (stderr, "subprocess terminated with unexpected wait status %d\n", status);
+      return 4;
+    }
+  exitstatus = WEXITSTATUS (status);
+  if (exitstatus != 0)
+    {
+      fprintf (stderr, "subprocess terminated with unexpected exit status %d\n", exitstatus);
+      return 5;
+    }
+  return 0;
+}
+
+static int
+child_main (void)
+{
+  char buf[1024];
+
+  /* See if reading from STDIN_FILENO yields the expected contents.  */
+  if (fread (buf, 1, sizeof (buf), stdin) == 11
+      && memcmp (buf, "Halle Potta", 11) == 0)
+    return 0;
+  else
+    return 8;
+}
+
+static void
+cleanup_then_die (int sig)
+{
+  /* Clean up data file.  */
+  unlink (DATA_FILENAME);
+
+  /* Re-raise the signal and die from it.  */
+  signal (sig, SIG_DFL);
+  raise (sig);
+}
+
+int
+main (int argc, char *argv[])
+{
+  int exitstatus;
+
+  if (!(argc > 1 && strcmp (argv[1], "-child") == 0))
+    {
+      /* This is the parent process.  */
+      signal (SIGINT, cleanup_then_die);
+      signal (SIGTERM, cleanup_then_die);
+      #ifdef SIGHUP
+      signal (SIGHUP, cleanup_then_die);
+      #endif
+
+      exitstatus = parent_main ();
+    }
+  else
+    {
+      /* This is the child process.  */
+
+      exitstatus = child_main ();
+    }
+  unlink (DATA_FILENAME);
+  return exitstatus;
+}
+]])],
+           [],
+           [gl_cv_func_posix_spawn_works=no])
+       fi
+     else
+       case "$host_os" in
+         aix*) gl_cv_func_posix_spawn_works="guessing no";;
+         *)    gl_cv_func_posix_spawn_works="guessing yes";;
+       esac
+     fi
+    ])
+])
+
+dnl Test whether posix_spawn and posix_spawnp are secure.
+AC_DEFUN([gl_POSIX_SPAWN_SECURE],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  dnl On many platforms, posix_spawn or posix_spawnp allow executing a
+  dnl script without a '#!' marker as a shell script. This is unsecure.
+  AC_CACHE_CHECK([whether posix_spawn rejects scripts without shebang],
+    [gl_cv_func_posix_spawn_secure_exec],
+    [echo ':' > conftest.scr
+     chmod a+x conftest.scr
+     AC_RUN_IFELSE([AC_LANG_SOURCE([[
+       #include <errno.h>
+       #include <spawn.h>
+       #include <stddef.h>
+       #include <sys/types.h>
+       #include <sys/wait.h>
+       int
+       main ()
+       {
+         const char *prog_path = "./conftest.scr";
+         const char *prog_argv[2] = { prog_path, NULL };
+         const char *environment[2] = { "PATH=.", NULL };
+         pid_t child;
+         int status;
+         int err = posix_spawn (&child, prog_path, NULL, NULL,
+                                (char **) prog_argv, (char **) environment);
+         if (err == ENOEXEC)
+           return 0;
+         if (err != 0)
+           return 1;
+         status = 0;
+         while (waitpid (child, &status, 0) != child)
+           ;
+         if (!WIFEXITED (status))
+           return 2;
+         if (WEXITSTATUS (status) != 127)
+           return 3;
+         return 0;
+       }
+       ]])],
+       [gl_cv_func_posix_spawn_secure_exec=yes],
+       [gl_cv_func_posix_spawn_secure_exec=no],
+       [case "$host_os" in
+          # Guess no on GNU/Hurd.
+          gnu*)
+            gl_cv_func_posix_spawn_secure_exec="guessing no" ;;
+          # Guess yes on all other platforms.
+          *)
+            gl_cv_func_posix_spawn_secure_exec="guessing yes" ;;
+        esac
+       ])
+     rm -f conftest.scr
+    ])
+  AC_CACHE_CHECK([whether posix_spawnp rejects scripts without shebang],
+    [gl_cv_func_posix_spawnp_secure_exec],
+    [echo ':' > conftest.scr
+     chmod a+x conftest.scr
+     AC_RUN_IFELSE([AC_LANG_SOURCE([[
+       #include <errno.h>
+       #include <spawn.h>
+       #include <stddef.h>
+       #include <sys/types.h>
+       #include <sys/wait.h>
+       int
+       main ()
+       {
+         const char *prog_path = "./conftest.scr";
+         const char *prog_argv[2] = { prog_path, NULL };
+         const char *environment[2] = { "PATH=.", NULL };
+         pid_t child;
+         int status;
+         int err = posix_spawnp (&child, prog_path, NULL, NULL,
+                                 (char **) prog_argv, (char **) environment);
+         if (err == ENOEXEC)
+           return 0;
+         if (err != 0)
+           return 1;
+         status = 0;
+         while (waitpid (child, &status, 0) != child)
+           ;
+         if (!WIFEXITED (status))
+           return 2;
+         if (WEXITSTATUS (status) != 127)
+           return 3;
+         return 0;
+       }
+       ]])],
+       [gl_cv_func_posix_spawnp_secure_exec=yes],
+       [gl_cv_func_posix_spawnp_secure_exec=no],
+       [case "$host_os" in
+          # Guess yes on glibc systems (glibc >= 2.15 actually) except GNU/Hurd,
+          # musl libc, NetBSD.
+          *-gnu* | *-musl* | netbsd*)
+            gl_cv_func_posix_spawnp_secure_exec="guessing yes" ;;
+          # Guess no on GNU/Hurd, macOS, FreeBSD, OpenBSD, AIX, Solaris, Cygwin.
+          gnu* | darwin* | freebsd* | dragonfly* | openbsd* | aix* | solaris* | cygwin*)
+            gl_cv_func_posix_spawnp_secure_exec="guessing no" ;;
+          # If we don't know, obey --enable-cross-guesses.
+          *)
+            gl_cv_func_posix_spawnp_secure_exec="$gl_cross_guess_normal" ;;
+        esac
+       ])
+     rm -f conftest.scr
+    ])
+])
+
+# Prerequisites of lib/spawni.c.
+AC_DEFUN([gl_PREREQ_POSIX_SPAWN_INTERNAL],
+[
+  AC_CHECK_HEADERS([paths.h])
+  AC_CHECK_FUNCS([confstr sched_setparam sched_setscheduler setegid seteuid vfork])
+])
+
+AC_DEFUN([gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE],
+[
+  AC_REQUIRE([gl_SPAWN_H_DEFAULTS])
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  gl_POSIX_SPAWN
+  if test $REPLACE_POSIX_SPAWN = 1; then
+    REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE=1
+  else
+    dnl On musl libc and Solaris 11.0, posix_spawn_file_actions_addclose
+    dnl succeeds even if the fd argument is out of range.
+    AC_CACHE_CHECK([whether posix_spawn_file_actions_addclose works],
+      [gl_cv_func_posix_spawn_file_actions_addclose_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_SOURCE([[
+#include <spawn.h>
+int main ()
+{
+  posix_spawn_file_actions_t actions;
+  if (posix_spawn_file_actions_init (&actions) != 0)
+    return 1;
+  if (posix_spawn_file_actions_addclose (&actions, 10000000) == 0)
+    return 2;
+  return 0;
+}]])],
+         [gl_cv_func_posix_spawn_file_actions_addclose_works=yes],
+         [gl_cv_func_posix_spawn_file_actions_addclose_works=no],
+         [# Guess no on musl libc and Solaris, yes otherwise.
+          case "$host_os" in
+            *-musl*)  gl_cv_func_posix_spawn_file_actions_addclose_works="guessing no" ;;
+            solaris*) gl_cv_func_posix_spawn_file_actions_addclose_works="guessing no" ;;
+                      # Guess no on native Windows.
+            mingw*)   gl_cv_func_posix_spawn_file_actions_addclose_works="guessing no" ;;
+            *)        gl_cv_func_posix_spawn_file_actions_addclose_works="guessing yes" ;;
+          esac
+         ])
+      ])
+    case "$gl_cv_func_posix_spawn_file_actions_addclose_works" in
+      *yes) ;;
+      *) REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE=1 ;;
+    esac
+  fi
+])
+
+AC_DEFUN([gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2],
+[
+  AC_REQUIRE([gl_SPAWN_H_DEFAULTS])
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  gl_POSIX_SPAWN
+  if test $REPLACE_POSIX_SPAWN = 1; then
+    REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2=1
+  else
+    dnl On musl libc and Solaris 11.0, posix_spawn_file_actions_adddup2
+    dnl succeeds even if the fd argument is out of range.
+    AC_CACHE_CHECK([whether posix_spawn_file_actions_adddup2 works],
+      [gl_cv_func_posix_spawn_file_actions_adddup2_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_SOURCE([[
+#include <spawn.h>
+int main ()
+{
+  posix_spawn_file_actions_t actions;
+  if (posix_spawn_file_actions_init (&actions) != 0)
+    return 1;
+  if (posix_spawn_file_actions_adddup2 (&actions, 10000000, 2) == 0)
+    return 2;
+  return 0;
+}]])],
+         [gl_cv_func_posix_spawn_file_actions_adddup2_works=yes],
+         [gl_cv_func_posix_spawn_file_actions_adddup2_works=no],
+         [# Guess no on musl libc and Solaris, yes otherwise.
+          case "$host_os" in
+            *-musl*)  gl_cv_func_posix_spawn_file_actions_adddup2_works="guessing no";;
+            solaris*) gl_cv_func_posix_spawn_file_actions_adddup2_works="guessing no";;
+                      # Guess no on native Windows.
+            mingw*)   gl_cv_func_posix_spawn_file_actions_adddup2_works="guessing no" ;;
+            *)        gl_cv_func_posix_spawn_file_actions_adddup2_works="guessing yes";;
+          esac
+         ])
+      ])
+    case "$gl_cv_func_posix_spawn_file_actions_adddup2_works" in
+      *yes) ;;
+      *) REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2=1 ;;
+    esac
+  fi
+])
+
+AC_DEFUN([gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN],
+[
+  AC_REQUIRE([gl_SPAWN_H_DEFAULTS])
+  AC_REQUIRE([AC_PROG_CC])
+  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+  gl_POSIX_SPAWN
+  if test $REPLACE_POSIX_SPAWN = 1; then
+    REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN=1
+  else
+    dnl On musl libc and Solaris 11.0, posix_spawn_file_actions_addopen
+    dnl succeeds even if the fd argument is out of range.
+    AC_CACHE_CHECK([whether posix_spawn_file_actions_addopen works],
+      [gl_cv_func_posix_spawn_file_actions_addopen_works],
+      [AC_RUN_IFELSE(
+         [AC_LANG_SOURCE([[
+#include <spawn.h>
+#include <fcntl.h>
+int main ()
+{
+  posix_spawn_file_actions_t actions;
+  if (posix_spawn_file_actions_init (&actions) != 0)
+    return 1;
+  if (posix_spawn_file_actions_addopen (&actions, 10000000, "foo", 0, O_RDONLY)
+      == 0)
+    return 2;
+  return 0;
+}]])],
+         [gl_cv_func_posix_spawn_file_actions_addopen_works=yes],
+         [gl_cv_func_posix_spawn_file_actions_addopen_works=no],
+         [# Guess no on musl libc and Solaris, yes otherwise.
+          case "$host_os" in
+            *-musl*)  gl_cv_func_posix_spawn_file_actions_addopen_works="guessing no";;
+            solaris*) gl_cv_func_posix_spawn_file_actions_addopen_works="guessing no";;
+                      # Guess no on native Windows.
+            mingw*)   gl_cv_func_posix_spawn_file_actions_addopen_works="guessing no" ;;
+            *)        gl_cv_func_posix_spawn_file_actions_addopen_works="guessing yes";;
+          esac
+         ])
+      ])
+    case "$gl_cv_func_posix_spawn_file_actions_addopen_works" in
+      *yes) ;;
+      *) REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN=1 ;;
+    esac
+  fi
+])
diff --git a/m4/posix_spawn_faction_addchdir.m4 b/m4/posix_spawn_faction_addchdir.m4
new file mode 100644
index 00000000000..1ce7153d1d1
--- /dev/null
+++ b/m4/posix_spawn_faction_addchdir.m4
@@ -0,0 +1,20 @@
+# posix_spawn_faction_addchdir.m4 serial 1
+dnl Copyright (C) 2018-2020 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR],
+[
+  AC_REQUIRE([gl_SPAWN_H_DEFAULTS])
+  AC_REQUIRE([AC_PROG_CC])
+  gl_POSIX_SPAWN
+  AC_CHECK_FUNCS_ONCE([posix_spawn_file_actions_addchdir posix_spawn_file_actions_addchdir_np])
+  if test $ac_cv_func_posix_spawn_file_actions_addchdir = yes; then
+    dnl This function is not yet standardized. Therefore override the
+    dnl system's implementation always.
+    REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=1
+  else
+    HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=0
+  fi
+])
diff --git a/m4/sched_h.m4 b/m4/sched_h.m4
new file mode 100644
index 00000000000..af0c43de079
--- /dev/null
+++ b/m4/sched_h.m4
@@ -0,0 +1,91 @@
+# sched_h.m4 serial 12
+dnl Copyright (C) 2008-2020 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Written by Bruno Haible.
+
+AC_DEFUN([gl_SCHED_H],
+[
+  dnl Use AC_REQUIRE here, so that the default behavior below is expanded
+  dnl once only, before all statements that occur in other macros.
+  AC_REQUIRE([gl_SCHED_H_DEFAULTS])
+
+  AC_REQUIRE([AC_CANONICAL_HOST])
+
+  AC_CHECK_HEADERS_ONCE([sys/cdefs.h])
+  AC_CHECK_HEADERS([sched.h], [], [],
+    [[#if HAVE_SYS_CDEFS_H
+       #include <sys/cdefs.h>
+      #endif
+    ]])
+  gl_NEXT_HEADERS([sched.h])
+
+  if test "$ac_cv_header_sched_h" = yes; then
+    HAVE_SCHED_H=1
+  else
+    HAVE_SCHED_H=0
+  fi
+  AC_SUBST([HAVE_SCHED_H])
+
+  if test "$HAVE_SCHED_H" = 1; then
+    AC_CHECK_TYPE([struct sched_param],
+      [HAVE_STRUCT_SCHED_PARAM=1], [HAVE_STRUCT_SCHED_PARAM=0],
+      [[#if HAVE_SYS_CDEFS_H
+         #include <sys/cdefs.h>
+        #endif
+        #include <sched.h>
+      ]])
+  else
+    HAVE_STRUCT_SCHED_PARAM=0
+    case "$host_os" in
+      os2*)
+        dnl On OS/2 kLIBC, struct sched_param is in spawn.h.
+        AC_CHECK_TYPE([struct sched_param],
+          [HAVE_STRUCT_SCHED_PARAM=1], [],
+          [#include <spawn.h>])
+        ;;
+      vms)
+        dnl On OpenVMS 7.2 or newer, struct sched_param is in pthread.h.
+        AC_CHECK_TYPE([struct sched_param],
+          [HAVE_STRUCT_SCHED_PARAM=1], [],
+          [#include <pthread.h>])
+        ;;
+    esac
+  fi
+  AC_SUBST([HAVE_STRUCT_SCHED_PARAM])
+
+  if test "$ac_cv_header_sys_cdefs_h" = yes; then
+    HAVE_SYS_CDEFS_H=1
+  else
+    HAVE_SYS_CDEFS_H=0
+  fi
+  AC_SUBST([HAVE_SYS_CDEFS_H])
+
+  dnl Ensure the type pid_t gets defined.
+  AC_REQUIRE([AC_TYPE_PID_T])
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use, if it is not common
+  dnl enough to be declared everywhere.
+  gl_WARN_ON_USE_PREPARE([[#include <sched.h>
+    ]], [sched_yield])
+])
+
+AC_DEFUN([gl_SCHED_MODULE_INDICATOR],
+[
+  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
+  AC_REQUIRE([gl_SCHED_H_DEFAULTS])
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+AC_DEFUN([gl_SCHED_H_DEFAULTS],
+[
+  GNULIB_SCHED_YIELD=0;  AC_SUBST([GNULIB_SCHED_YIELD])
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_SCHED_YIELD=1;    AC_SUBST([HAVE_SCHED_YIELD])
+  REPLACE_SCHED_YIELD=0; AC_SUBST([REPLACE_SCHED_YIELD])
+])
diff --git a/m4/sh-filename.m4 b/m4/sh-filename.m4
new file mode 100644
index 00000000000..f7b31548e0d
--- /dev/null
+++ b/m4/sh-filename.m4
@@ -0,0 +1,22 @@
+# sh-filename.m4 serial 2
+dnl Copyright (C) 2018-2020 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl From Bruno Haible.
+
+AC_DEFUN([gl_SH_FILENAME],
+[
+  AH_VERBATIM([SH_FILENAME],
+[/* File name of the Bourne shell.  */
+#if defined __CYGWIN__ || defined __ANDROID__
+/* Omit the directory part because
+   - For 32-bit Cygwin programs in a 64-bit Cygwin environment, the Cygwin
+     mounts are not visible.
+   - On Android, /bin/sh does not exist. It's /system/bin/sh instead.  */
+# define BOURNE_SHELL "sh"
+#else
+# define BOURNE_SHELL "/bin/sh"
+#endif])
+])
diff --git a/m4/spawn_h.m4 b/m4/spawn_h.m4
new file mode 100644
index 00000000000..781f9f49652
--- /dev/null
+++ b/m4/spawn_h.m4
@@ -0,0 +1,136 @@
+# spawn_h.m4 serial 18
+dnl Copyright (C) 2008-2020 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Written by Bruno Haible.
+
+AC_DEFUN([gl_SPAWN_H],
+[
+  dnl Use AC_REQUIRE here, so that the default behavior below is expanded
+  dnl once only, before all statements that occur in other macros.
+  AC_REQUIRE([gl_SPAWN_H_DEFAULTS])
+
+  dnl <spawn.h> is always overridden, because of GNULIB_POSIXCHECK.
+  gl_CHECK_NEXT_HEADERS([spawn.h])
+
+  if test $ac_cv_header_spawn_h = yes; then
+    HAVE_SPAWN_H=1
+    AC_CHECK_TYPES([posix_spawnattr_t], [], [HAVE_POSIX_SPAWNATTR_T=0], [[
+#include <spawn.h>
+      ]])
+    AC_CHECK_TYPES([posix_spawn_file_actions_t], [],
+      [HAVE_POSIX_SPAWN_FILE_ACTIONS_T=0], [[
+#include <spawn.h>
+      ]])
+  else
+    HAVE_SPAWN_H=0
+    HAVE_POSIX_SPAWNATTR_T=0
+    HAVE_POSIX_SPAWN_FILE_ACTIONS_T=0
+  fi
+  AC_SUBST([HAVE_SPAWN_H])
+
+  dnl Ensure the type pid_t gets defined.
+  AC_REQUIRE([AC_TYPE_PID_T])
+
+  dnl Ensure the type mode_t gets defined.
+  AC_REQUIRE([AC_TYPE_MODE_T])
+
+  AC_REQUIRE([gl_HAVE_POSIX_SPAWN])
+
+  AC_REQUIRE([AC_C_RESTRICT])
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use.
+  gl_WARN_ON_USE_PREPARE([[#include <spawn.h>
+    ]], [posix_spawn posix_spawnp posix_spawnattr_init posix_spawnattr_destroy
+    posix_spawnattr_getsigdefault posix_spawnattr_setsigdefault
+    posix_spawnattr_getsigmask posix_spawnattr_setsigmask
+    posix_spawnattr_getflags posix_spawnattr_setflags
+    posix_spawnattr_getpgroup posix_spawnattr_setpgroup
+    posix_spawnattr_getschedpolicy posix_spawnattr_setschedpolicy
+    posix_spawnattr_getschedparam posix_spawnattr_setschedparam
+    posix_spawn_file_actions_init posix_spawn_file_actions_destroy
+    posix_spawn_file_actions_addopen posix_spawn_file_actions_addclose
+    posix_spawn_file_actions_adddup2 posix_spawn_file_actions_addchdir
+    posix_spawn_file_actions_addfchdir])
+])
+
+dnl Checks whether the system has the functions posix_spawn.
+dnl Sets ac_cv_func_posix_spawn and HAVE_POSIX_SPAWN.
+AC_DEFUN([gl_HAVE_POSIX_SPAWN],
+[
+  dnl Use AC_REQUIRE here, so that the default behavior below is expanded
+  dnl once only, before all statements that occur in other macros.
+  AC_REQUIRE([gl_SPAWN_H_DEFAULTS])
+
+  LIB_POSIX_SPAWN=
+  AC_SUBST([LIB_POSIX_SPAWN])
+  gl_saved_libs=$LIBS
+    AC_SEARCH_LIBS([posix_spawn], [rt],
+                   [test "$ac_cv_search_posix_spawn" = "none required" ||
+                    LIB_POSIX_SPAWN=$ac_cv_search_posix_spawn])
+    AC_CHECK_FUNCS([posix_spawn])
+  LIBS=$gl_saved_libs
+
+  if test $ac_cv_func_posix_spawn != yes; then
+    HAVE_POSIX_SPAWN=0
+  fi
+])
+
+AC_DEFUN([gl_SPAWN_MODULE_INDICATOR],
+[
+  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
+  AC_REQUIRE([gl_SPAWN_H_DEFAULTS])
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+AC_DEFUN([gl_SPAWN_H_DEFAULTS],
+[
+  GNULIB_POSIX_SPAWN=0;                        AC_SUBST([GNULIB_POSIX_SPAWN])
+  GNULIB_POSIX_SPAWNP=0;                       AC_SUBST([GNULIB_POSIX_SPAWNP])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_INIT=0;      AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_INIT])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=0;  AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE=0;  AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2=0;   AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR=0; AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN=0;   AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN])
+  GNULIB_POSIX_SPAWN_FILE_ACTIONS_DESTROY=0;   AC_SUBST([GNULIB_POSIX_SPAWN_FILE_ACTIONS_DESTROY])
+  GNULIB_POSIX_SPAWNATTR_INIT=0;               AC_SUBST([GNULIB_POSIX_SPAWNATTR_INIT])
+  GNULIB_POSIX_SPAWNATTR_GETFLAGS=0;           AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETFLAGS])
+  GNULIB_POSIX_SPAWNATTR_SETFLAGS=0;           AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETFLAGS])
+  GNULIB_POSIX_SPAWNATTR_GETPGROUP=0;          AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETPGROUP])
+  GNULIB_POSIX_SPAWNATTR_SETPGROUP=0;          AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETPGROUP])
+  GNULIB_POSIX_SPAWNATTR_GETSCHEDPARAM=0;      AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSCHEDPARAM])
+  GNULIB_POSIX_SPAWNATTR_SETSCHEDPARAM=0;      AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSCHEDPARAM])
+  GNULIB_POSIX_SPAWNATTR_GETSCHEDPOLICY=0;     AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSCHEDPOLICY])
+  GNULIB_POSIX_SPAWNATTR_SETSCHEDPOLICY=0;     AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSCHEDPOLICY])
+  GNULIB_POSIX_SPAWNATTR_GETSIGDEFAULT=0;      AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSIGDEFAULT])
+  GNULIB_POSIX_SPAWNATTR_SETSIGDEFAULT=0;      AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSIGDEFAULT])
+  GNULIB_POSIX_SPAWNATTR_GETSIGMASK=0;         AC_SUBST([GNULIB_POSIX_SPAWNATTR_GETSIGMASK])
+  GNULIB_POSIX_SPAWNATTR_SETSIGMASK=0;         AC_SUBST([GNULIB_POSIX_SPAWNATTR_SETSIGMASK])
+  GNULIB_POSIX_SPAWNATTR_DESTROY=0;            AC_SUBST([GNULIB_POSIX_SPAWNATTR_DESTROY])
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  HAVE_POSIX_SPAWN=1;        AC_SUBST([HAVE_POSIX_SPAWN])
+  HAVE_POSIX_SPAWNATTR_T=1;  AC_SUBST([HAVE_POSIX_SPAWNATTR_T])
+  HAVE_POSIX_SPAWN_FILE_ACTIONS_T=1;
+                             AC_SUBST([HAVE_POSIX_SPAWN_FILE_ACTIONS_T])
+  HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=1;
+                             AC_SUBST([HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR])
+  HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR=1;
+                             AC_SUBST([HAVE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR])
+  REPLACE_POSIX_SPAWN=0;     AC_SUBST([REPLACE_POSIX_SPAWN])
+  REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR=0;
+                             AC_SUBST([REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCHDIR])
+  REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE=0;
+                             AC_SUBST([REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDCLOSE])
+  REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2=0;
+                             AC_SUBST([REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDDUP2])
+  REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR=0;
+                             AC_SUBST([REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDFCHDIR])
+  REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN=0;
+                             AC_SUBST([REPLACE_POSIX_SPAWN_FILE_ACTIONS_ADDOPEN])
+])
diff --git a/m4/strchrnul.m4 b/m4/strchrnul.m4
new file mode 100644
index 00000000000..a18f0935a51
--- /dev/null
+++ b/m4/strchrnul.m4
@@ -0,0 +1,50 @@
+# strchrnul.m4 serial 9
+dnl Copyright (C) 2003, 2007, 2009-2020 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_FUNC_STRCHRNUL],
+[
+  dnl Persuade glibc <string.h> to declare strchrnul().
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  AC_CHECK_FUNCS([strchrnul])
+  if test $ac_cv_func_strchrnul = no; then
+    HAVE_STRCHRNUL=0
+  else
+    AC_CACHE_CHECK([whether strchrnul works],
+      [gl_cv_func_strchrnul_works],
+      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <string.h> /* for strchrnul */
+]], [[const char *buf = "a";
+      return strchrnul (buf, 'b') != buf + 1;
+    ]])],
+        [gl_cv_func_strchrnul_works=yes],
+        [gl_cv_func_strchrnul_works=no],
+        [dnl Cygwin 1.7.9 introduced strchrnul, but it was broken until 1.7.10
+         AC_EGREP_CPP([Lucky user],
+           [
+#if defined __CYGWIN__
+ #include <cygwin/version.h>
+ #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 9)
+  Lucky user
+ #endif
+#else
+  Lucky user
+#endif
+           ],
+           [gl_cv_func_strchrnul_works="guessing yes"],
+           [gl_cv_func_strchrnul_works="guessing no"])
+        ])
+      ])
+    case "$gl_cv_func_strchrnul_works" in
+      *yes) ;;
+      *) REPLACE_STRCHRNUL=1 ;;
+    esac
+  fi
+])
+
+# Prerequisites of lib/strchrnul.c.
+AC_DEFUN([gl_PREREQ_STRCHRNUL], [:])